From 089349e2a5c5c1d202ea47df3d01966dfe762280 Mon Sep 17 00:00:00 2001
From: Nikolai Prokoschenko <nikolai.prokoschenko@kurzdigital.com>
Date: Mon, 3 Jun 2024 10:59:07 +0200
Subject: [PATCH] Address comments on the "rootless CA certs" patch

Address the following problems with #538:

1. Correct the shell selection for entrypoint, Ubuntu flavours still need explicit `bash` for variables with dots in
their names
2. Change unhelpful exported variable name (changed from `CACERT` to `JRE_CACERTS_PATH`)
3. Change `which` to more-POSIX-compatible `command -v`
4. More cleanup
5. Explicitely use `TMPDIR` when available instead of hard-coded `/tmp`
---
 .../tests/java-ca-certificates-update/run.sh  |  2 +-
 11/jdk/alpine/entrypoint.sh                   | 39 +++++++++++--------
 11/jdk/centos/entrypoint.sh                   | 39 +++++++++++--------
 11/jdk/ubi/ubi9-minimal/entrypoint.sh         | 39 +++++++++++--------
 11/jdk/ubuntu/focal/Dockerfile                |  2 +-
 11/jdk/ubuntu/focal/entrypoint.sh             | 39 +++++++++++--------
 11/jdk/ubuntu/jammy/Dockerfile                |  2 +-
 11/jdk/ubuntu/jammy/entrypoint.sh             | 39 +++++++++++--------
 11/jre/alpine/entrypoint.sh                   | 39 +++++++++++--------
 11/jre/centos/entrypoint.sh                   | 39 +++++++++++--------
 11/jre/ubi/ubi9-minimal/entrypoint.sh         | 39 +++++++++++--------
 11/jre/ubuntu/focal/Dockerfile                |  2 +-
 11/jre/ubuntu/focal/entrypoint.sh             | 39 +++++++++++--------
 11/jre/ubuntu/jammy/Dockerfile                |  2 +-
 11/jre/ubuntu/jammy/entrypoint.sh             | 39 +++++++++++--------
 17/jdk/alpine/entrypoint.sh                   | 39 +++++++++++--------
 17/jdk/centos/entrypoint.sh                   | 39 +++++++++++--------
 17/jdk/ubi/ubi9-minimal/entrypoint.sh         | 39 +++++++++++--------
 17/jdk/ubuntu/focal/Dockerfile                |  2 +-
 17/jdk/ubuntu/focal/entrypoint.sh             | 39 +++++++++++--------
 17/jdk/ubuntu/jammy/Dockerfile                |  2 +-
 17/jdk/ubuntu/jammy/entrypoint.sh             | 39 +++++++++++--------
 17/jre/alpine/entrypoint.sh                   | 39 +++++++++++--------
 17/jre/centos/entrypoint.sh                   | 39 +++++++++++--------
 17/jre/ubi/ubi9-minimal/entrypoint.sh         | 39 +++++++++++--------
 17/jre/ubuntu/focal/Dockerfile                |  2 +-
 17/jre/ubuntu/focal/entrypoint.sh             | 39 +++++++++++--------
 17/jre/ubuntu/jammy/Dockerfile                |  2 +-
 17/jre/ubuntu/jammy/entrypoint.sh             | 39 +++++++++++--------
 21/jdk/alpine/entrypoint.sh                   | 39 +++++++++++--------
 21/jdk/ubi/ubi9-minimal/entrypoint.sh         | 39 +++++++++++--------
 21/jdk/ubuntu/jammy/Dockerfile                |  2 +-
 21/jdk/ubuntu/jammy/entrypoint.sh             | 39 +++++++++++--------
 21/jre/alpine/entrypoint.sh                   | 39 +++++++++++--------
 21/jre/ubi/ubi9-minimal/entrypoint.sh         | 39 +++++++++++--------
 21/jre/ubuntu/jammy/Dockerfile                |  2 +-
 21/jre/ubuntu/jammy/entrypoint.sh             | 39 +++++++++++--------
 22/jdk/alpine/entrypoint.sh                   | 39 +++++++++++--------
 22/jdk/ubi/ubi9-minimal/entrypoint.sh         | 39 +++++++++++--------
 22/jdk/ubuntu/jammy/Dockerfile                |  2 +-
 22/jdk/ubuntu/jammy/entrypoint.sh             | 39 +++++++++++--------
 22/jre/alpine/entrypoint.sh                   | 39 +++++++++++--------
 22/jre/ubi/ubi9-minimal/entrypoint.sh         | 39 +++++++++++--------
 22/jre/ubuntu/jammy/Dockerfile                |  2 +-
 22/jre/ubuntu/jammy/entrypoint.sh             | 39 +++++++++++--------
 8/jdk/alpine/entrypoint.sh                    | 39 +++++++++++--------
 8/jdk/centos/entrypoint.sh                    | 39 +++++++++++--------
 8/jdk/ubi/ubi9-minimal/entrypoint.sh          | 39 +++++++++++--------
 8/jdk/ubuntu/focal/Dockerfile                 |  2 +-
 8/jdk/ubuntu/focal/entrypoint.sh              | 39 +++++++++++--------
 8/jdk/ubuntu/jammy/Dockerfile                 |  2 +-
 8/jdk/ubuntu/jammy/entrypoint.sh              | 39 +++++++++++--------
 8/jre/alpine/entrypoint.sh                    | 39 +++++++++++--------
 8/jre/centos/entrypoint.sh                    | 39 +++++++++++--------
 8/jre/ubi/ubi9-minimal/entrypoint.sh          | 39 +++++++++++--------
 8/jre/ubuntu/focal/Dockerfile                 |  2 +-
 8/jre/ubuntu/focal/entrypoint.sh              | 39 +++++++++++--------
 8/jre/ubuntu/jammy/Dockerfile                 |  2 +-
 8/jre/ubuntu/jammy/entrypoint.sh              | 39 +++++++++++--------
 config/hotspot.yml                            |  6 +++
 docker_templates/entrypoint.sh                | 39 +++++++++++--------
 docker_templates/ubuntu.Dockerfile.j2         |  4 +-
 generate_dockerfiles.py                       |  2 +
 63 files changed, 1016 insertions(+), 707 deletions(-)
 mode change 100755 => 100644 docker_templates/entrypoint.sh

diff --git a/.test/tests/java-ca-certificates-update/run.sh b/.test/tests/java-ca-certificates-update/run.sh
index 7c883fa19..3ad348b53 100755
--- a/.test/tests/java-ca-certificates-update/run.sh
+++ b/.test/tests/java-ca-certificates-update/run.sh
@@ -10,7 +10,7 @@ CMD1=date
 
 # CMD2 in each run is to check for the `dockerbuilder` certificate in the Java keystore. Entrypoint export $CACERT to
 # point to the Java keystore.
-CMD2=(sh -c "keytool -list -keystore \$CACERT -storepass changeit -alias dockerbuilder")
+CMD2=(sh -c "keytool -list -keystore \"\$JRE_CACERTS_PATH\" -storepass changeit -alias dockerbuilder")
 
 # For a custom entrypoint test, we need to create a new image. This image will get cleaned up at the end of the script
 # by the `finish` trap function.
diff --git a/11/jdk/alpine/entrypoint.sh b/11/jdk/alpine/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/11/jdk/alpine/entrypoint.sh
+++ b/11/jdk/alpine/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/11/jdk/centos/entrypoint.sh b/11/jdk/centos/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/11/jdk/centos/entrypoint.sh
+++ b/11/jdk/centos/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/11/jdk/ubi/ubi9-minimal/entrypoint.sh b/11/jdk/ubi/ubi9-minimal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/11/jdk/ubi/ubi9-minimal/entrypoint.sh
+++ b/11/jdk/ubi/ubi9-minimal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/11/jdk/ubuntu/focal/Dockerfile b/11/jdk/ubuntu/focal/Dockerfile
index b4a2286a3..c76f99a27 100644
--- a/11/jdk/ubuntu/focal/Dockerfile
+++ b/11/jdk/ubuntu/focal/Dockerfile
@@ -100,6 +100,6 @@ RUN set -eux; \
     echo "java --version"; java --version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
 
 CMD ["jshell"]
diff --git a/11/jdk/ubuntu/focal/entrypoint.sh b/11/jdk/ubuntu/focal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/11/jdk/ubuntu/focal/entrypoint.sh
+++ b/11/jdk/ubuntu/focal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/11/jdk/ubuntu/jammy/Dockerfile b/11/jdk/ubuntu/jammy/Dockerfile
index 8493bffa7..aec104372 100644
--- a/11/jdk/ubuntu/jammy/Dockerfile
+++ b/11/jdk/ubuntu/jammy/Dockerfile
@@ -100,6 +100,6 @@ RUN set -eux; \
     echo "java --version"; java --version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
 
 CMD ["jshell"]
diff --git a/11/jdk/ubuntu/jammy/entrypoint.sh b/11/jdk/ubuntu/jammy/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/11/jdk/ubuntu/jammy/entrypoint.sh
+++ b/11/jdk/ubuntu/jammy/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/11/jre/alpine/entrypoint.sh b/11/jre/alpine/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/11/jre/alpine/entrypoint.sh
+++ b/11/jre/alpine/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/11/jre/centos/entrypoint.sh b/11/jre/centos/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/11/jre/centos/entrypoint.sh
+++ b/11/jre/centos/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/11/jre/ubi/ubi9-minimal/entrypoint.sh b/11/jre/ubi/ubi9-minimal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/11/jre/ubi/ubi9-minimal/entrypoint.sh
+++ b/11/jre/ubi/ubi9-minimal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/11/jre/ubuntu/focal/Dockerfile b/11/jre/ubuntu/focal/Dockerfile
index 7b72337ac..9f63c996d 100644
--- a/11/jre/ubuntu/focal/Dockerfile
+++ b/11/jre/ubuntu/focal/Dockerfile
@@ -98,4 +98,4 @@ RUN set -eux; \
     echo "java --version"; java --version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
diff --git a/11/jre/ubuntu/focal/entrypoint.sh b/11/jre/ubuntu/focal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/11/jre/ubuntu/focal/entrypoint.sh
+++ b/11/jre/ubuntu/focal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/11/jre/ubuntu/jammy/Dockerfile b/11/jre/ubuntu/jammy/Dockerfile
index c9d67d7cb..d2fda1570 100644
--- a/11/jre/ubuntu/jammy/Dockerfile
+++ b/11/jre/ubuntu/jammy/Dockerfile
@@ -98,4 +98,4 @@ RUN set -eux; \
     echo "java --version"; java --version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
diff --git a/11/jre/ubuntu/jammy/entrypoint.sh b/11/jre/ubuntu/jammy/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/11/jre/ubuntu/jammy/entrypoint.sh
+++ b/11/jre/ubuntu/jammy/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/17/jdk/alpine/entrypoint.sh b/17/jdk/alpine/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/17/jdk/alpine/entrypoint.sh
+++ b/17/jdk/alpine/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/17/jdk/centos/entrypoint.sh b/17/jdk/centos/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/17/jdk/centos/entrypoint.sh
+++ b/17/jdk/centos/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/17/jdk/ubi/ubi9-minimal/entrypoint.sh b/17/jdk/ubi/ubi9-minimal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/17/jdk/ubi/ubi9-minimal/entrypoint.sh
+++ b/17/jdk/ubi/ubi9-minimal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/17/jdk/ubuntu/focal/Dockerfile b/17/jdk/ubuntu/focal/Dockerfile
index c4f9c82bf..03376e611 100644
--- a/17/jdk/ubuntu/focal/Dockerfile
+++ b/17/jdk/ubuntu/focal/Dockerfile
@@ -103,6 +103,6 @@ RUN set -eux; \
     echo "java --version"; java --version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
 
 CMD ["jshell"]
diff --git a/17/jdk/ubuntu/focal/entrypoint.sh b/17/jdk/ubuntu/focal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/17/jdk/ubuntu/focal/entrypoint.sh
+++ b/17/jdk/ubuntu/focal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/17/jdk/ubuntu/jammy/Dockerfile b/17/jdk/ubuntu/jammy/Dockerfile
index 18beaa010..73dd839be 100644
--- a/17/jdk/ubuntu/jammy/Dockerfile
+++ b/17/jdk/ubuntu/jammy/Dockerfile
@@ -103,6 +103,6 @@ RUN set -eux; \
     echo "java --version"; java --version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
 
 CMD ["jshell"]
diff --git a/17/jdk/ubuntu/jammy/entrypoint.sh b/17/jdk/ubuntu/jammy/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/17/jdk/ubuntu/jammy/entrypoint.sh
+++ b/17/jdk/ubuntu/jammy/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/17/jre/alpine/entrypoint.sh b/17/jre/alpine/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/17/jre/alpine/entrypoint.sh
+++ b/17/jre/alpine/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/17/jre/centos/entrypoint.sh b/17/jre/centos/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/17/jre/centos/entrypoint.sh
+++ b/17/jre/centos/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/17/jre/ubi/ubi9-minimal/entrypoint.sh b/17/jre/ubi/ubi9-minimal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/17/jre/ubi/ubi9-minimal/entrypoint.sh
+++ b/17/jre/ubi/ubi9-minimal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/17/jre/ubuntu/focal/Dockerfile b/17/jre/ubuntu/focal/Dockerfile
index 0d050c98b..497eb19a4 100644
--- a/17/jre/ubuntu/focal/Dockerfile
+++ b/17/jre/ubuntu/focal/Dockerfile
@@ -98,4 +98,4 @@ RUN set -eux; \
     echo "java --version"; java --version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
diff --git a/17/jre/ubuntu/focal/entrypoint.sh b/17/jre/ubuntu/focal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/17/jre/ubuntu/focal/entrypoint.sh
+++ b/17/jre/ubuntu/focal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/17/jre/ubuntu/jammy/Dockerfile b/17/jre/ubuntu/jammy/Dockerfile
index 951147b38..ce4e6f5dd 100644
--- a/17/jre/ubuntu/jammy/Dockerfile
+++ b/17/jre/ubuntu/jammy/Dockerfile
@@ -98,4 +98,4 @@ RUN set -eux; \
     echo "java --version"; java --version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
diff --git a/17/jre/ubuntu/jammy/entrypoint.sh b/17/jre/ubuntu/jammy/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/17/jre/ubuntu/jammy/entrypoint.sh
+++ b/17/jre/ubuntu/jammy/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/21/jdk/alpine/entrypoint.sh b/21/jdk/alpine/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/21/jdk/alpine/entrypoint.sh
+++ b/21/jdk/alpine/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/21/jdk/ubi/ubi9-minimal/entrypoint.sh b/21/jdk/ubi/ubi9-minimal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/21/jdk/ubi/ubi9-minimal/entrypoint.sh
+++ b/21/jdk/ubi/ubi9-minimal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/21/jdk/ubuntu/jammy/Dockerfile b/21/jdk/ubuntu/jammy/Dockerfile
index fb7d8197d..0a0d84718 100644
--- a/21/jdk/ubuntu/jammy/Dockerfile
+++ b/21/jdk/ubuntu/jammy/Dockerfile
@@ -99,6 +99,6 @@ RUN set -eux; \
     echo "java --version"; java --version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
 
 CMD ["jshell"]
diff --git a/21/jdk/ubuntu/jammy/entrypoint.sh b/21/jdk/ubuntu/jammy/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/21/jdk/ubuntu/jammy/entrypoint.sh
+++ b/21/jdk/ubuntu/jammy/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/21/jre/alpine/entrypoint.sh b/21/jre/alpine/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/21/jre/alpine/entrypoint.sh
+++ b/21/jre/alpine/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/21/jre/ubi/ubi9-minimal/entrypoint.sh b/21/jre/ubi/ubi9-minimal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/21/jre/ubi/ubi9-minimal/entrypoint.sh
+++ b/21/jre/ubi/ubi9-minimal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/21/jre/ubuntu/jammy/Dockerfile b/21/jre/ubuntu/jammy/Dockerfile
index 1a456e5b8..78549c8d5 100644
--- a/21/jre/ubuntu/jammy/Dockerfile
+++ b/21/jre/ubuntu/jammy/Dockerfile
@@ -94,4 +94,4 @@ RUN set -eux; \
     echo "java --version"; java --version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
diff --git a/21/jre/ubuntu/jammy/entrypoint.sh b/21/jre/ubuntu/jammy/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/21/jre/ubuntu/jammy/entrypoint.sh
+++ b/21/jre/ubuntu/jammy/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/22/jdk/alpine/entrypoint.sh b/22/jdk/alpine/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/22/jdk/alpine/entrypoint.sh
+++ b/22/jdk/alpine/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/22/jdk/ubi/ubi9-minimal/entrypoint.sh b/22/jdk/ubi/ubi9-minimal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/22/jdk/ubi/ubi9-minimal/entrypoint.sh
+++ b/22/jdk/ubi/ubi9-minimal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/22/jdk/ubuntu/jammy/Dockerfile b/22/jdk/ubuntu/jammy/Dockerfile
index f77d1c3cc..b4aec6628 100644
--- a/22/jdk/ubuntu/jammy/Dockerfile
+++ b/22/jdk/ubuntu/jammy/Dockerfile
@@ -93,6 +93,6 @@ RUN set -eux; \
     echo "java --version"; java --version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
 
 CMD ["jshell"]
diff --git a/22/jdk/ubuntu/jammy/entrypoint.sh b/22/jdk/ubuntu/jammy/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/22/jdk/ubuntu/jammy/entrypoint.sh
+++ b/22/jdk/ubuntu/jammy/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/22/jre/alpine/entrypoint.sh b/22/jre/alpine/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/22/jre/alpine/entrypoint.sh
+++ b/22/jre/alpine/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/22/jre/ubi/ubi9-minimal/entrypoint.sh b/22/jre/ubi/ubi9-minimal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/22/jre/ubi/ubi9-minimal/entrypoint.sh
+++ b/22/jre/ubi/ubi9-minimal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/22/jre/ubuntu/jammy/Dockerfile b/22/jre/ubuntu/jammy/Dockerfile
index 28f2117e9..9920eb707 100644
--- a/22/jre/ubuntu/jammy/Dockerfile
+++ b/22/jre/ubuntu/jammy/Dockerfile
@@ -88,4 +88,4 @@ RUN set -eux; \
     echo "java --version"; java --version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
diff --git a/22/jre/ubuntu/jammy/entrypoint.sh b/22/jre/ubuntu/jammy/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/22/jre/ubuntu/jammy/entrypoint.sh
+++ b/22/jre/ubuntu/jammy/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/8/jdk/alpine/entrypoint.sh b/8/jdk/alpine/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/8/jdk/alpine/entrypoint.sh
+++ b/8/jdk/alpine/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/8/jdk/centos/entrypoint.sh b/8/jdk/centos/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/8/jdk/centos/entrypoint.sh
+++ b/8/jdk/centos/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/8/jdk/ubi/ubi9-minimal/entrypoint.sh b/8/jdk/ubi/ubi9-minimal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/8/jdk/ubi/ubi9-minimal/entrypoint.sh
+++ b/8/jdk/ubi/ubi9-minimal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/8/jdk/ubuntu/focal/Dockerfile b/8/jdk/ubuntu/focal/Dockerfile
index f48185f2c..85beefb70 100644
--- a/8/jdk/ubuntu/focal/Dockerfile
+++ b/8/jdk/ubuntu/focal/Dockerfile
@@ -96,4 +96,4 @@ RUN set -eux; \
     echo "java -version"; java -version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
diff --git a/8/jdk/ubuntu/focal/entrypoint.sh b/8/jdk/ubuntu/focal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/8/jdk/ubuntu/focal/entrypoint.sh
+++ b/8/jdk/ubuntu/focal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/8/jdk/ubuntu/jammy/Dockerfile b/8/jdk/ubuntu/jammy/Dockerfile
index 2b4802316..3f64e880e 100644
--- a/8/jdk/ubuntu/jammy/Dockerfile
+++ b/8/jdk/ubuntu/jammy/Dockerfile
@@ -96,4 +96,4 @@ RUN set -eux; \
     echo "java -version"; java -version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
diff --git a/8/jdk/ubuntu/jammy/entrypoint.sh b/8/jdk/ubuntu/jammy/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/8/jdk/ubuntu/jammy/entrypoint.sh
+++ b/8/jdk/ubuntu/jammy/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/8/jre/alpine/entrypoint.sh b/8/jre/alpine/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/8/jre/alpine/entrypoint.sh
+++ b/8/jre/alpine/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/8/jre/centos/entrypoint.sh b/8/jre/centos/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/8/jre/centos/entrypoint.sh
+++ b/8/jre/centos/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/8/jre/ubi/ubi9-minimal/entrypoint.sh b/8/jre/ubi/ubi9-minimal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/8/jre/ubi/ubi9-minimal/entrypoint.sh
+++ b/8/jre/ubi/ubi9-minimal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/8/jre/ubuntu/focal/Dockerfile b/8/jre/ubuntu/focal/Dockerfile
index 086434ffd..b305b9357 100644
--- a/8/jre/ubuntu/focal/Dockerfile
+++ b/8/jre/ubuntu/focal/Dockerfile
@@ -95,4 +95,4 @@ RUN set -eux; \
     echo "java -version"; java -version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
diff --git a/8/jre/ubuntu/focal/entrypoint.sh b/8/jre/ubuntu/focal/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/8/jre/ubuntu/focal/entrypoint.sh
+++ b/8/jre/ubuntu/focal/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/8/jre/ubuntu/jammy/Dockerfile b/8/jre/ubuntu/jammy/Dockerfile
index bde0a5788..adb63ee59 100644
--- a/8/jre/ubuntu/jammy/Dockerfile
+++ b/8/jre/ubuntu/jammy/Dockerfile
@@ -95,4 +95,4 @@ RUN set -eux; \
     echo "java -version"; java -version; \
     echo "Complete."
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
+ENTRYPOINT ["/bin/bash", "/__cacert_entrypoint.sh"]
diff --git a/8/jre/ubuntu/jammy/entrypoint.sh b/8/jre/ubuntu/jammy/entrypoint.sh
index dfa0f703f..aa5738b12 100755
--- a/8/jre/ubuntu/jammy/entrypoint.sh
+++ b/8/jre/ubuntu/jammy/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/config/hotspot.yml b/config/hotspot.yml
index bc89374dc..9a82ca203 100644
--- a/config/hotspot.yml
+++ b/config/hotspot.yml
@@ -21,18 +21,24 @@ configurations:
   - directory: ubuntu/jammy
     image: ubuntu:22.04
     architectures: [aarch64, arm, ppc64le, s390x, x64]
+    # `bash` is required for Ubuntu-based images to correctly resolve
+    # environment variables.with.dots.in.them.
+    shebang: /bin/bash
     os: ubuntu
 
   - directory: ubuntu/focal
     architectures: [aarch64, arm, ppc64le, s390x, x64]
     image: ubuntu:20.04
     deprecated: 20
+    shebang: /bin/bash
     os: ubuntu
 
   - directory: centos
     architectures: [aarch64, ppc64le, x64]
     image: centos:7
     deprecated: 20
+    # CentOS's `/bin/sh` does not sanitize dotted variable names, so `bash` is unneeded
+    shebang: /bin/sh
     os: centos
 
   - directory: ubi/ubi9-minimal
diff --git a/docker_templates/entrypoint.sh b/docker_templates/entrypoint.sh
old mode 100755
new mode 100644
index dfa0f703f..aa5738b12
--- a/docker_templates/entrypoint.sh
+++ b/docker_templates/entrypoint.sh
@@ -1,34 +1,38 @@
 #!/usr/bin/env sh
-# Converted to POSIX shell to avoid the need for bash in the image
+# This script defines `sh` as the interpreter, which is available in all POSIX environments. However, it might get
+# started with `bash` as the shell to support dotted.environment.variable.names which are not supported by POSIX, but
+# are supported by `sh` in some Linux flavours.
 
 set -e
 
+TMPDIR=${TMPDIR:-/tmp}
+
 # JDK truststore location
-CACERT=$JAVA_HOME/lib/security/cacerts
+JRE_CACERTS_PATH=$JAVA_HOME/lib/security/cacerts
 
 # JDK8 puts its JRE in a subdirectory
 if [ -f "$JAVA_HOME/jre/lib/security/cacerts" ]; then
-    CACERT=$JAVA_HOME/jre/lib/security/cacerts
+    JRE_CACERTS_PATH=$JAVA_HOME/jre/lib/security/cacerts
 fi
 
 # Opt-in is only activated if the environment variable is set
 if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 
-    if [ ! -w /tmp ]; then
-        echo "Using additional CA certificates requires write permissions to /tmp. Cannot create truststore."
+    if [ ! -w "$TMPDIR" ]; then
+        echo "Using additional CA certificates requires write permissions to $TMPDIR. Cannot create truststore."
         exit 1
     fi
 
     # Figure out whether we can write to the JVM truststore. If we can, we'll add the certificates there. If not,
     # we'll use a temporary truststore.
-    if [ ! -w "$CACERT" ]; then
+    if [ ! -w "$JRE_CACERTS_PATH" ]; then
         # We cannot write to the JVM truststore, so we create a temporary one
-        CACERT_NEW=$(mktemp)
-        echo "Using a temporary truststore at $CACERT_NEW"
-        cp $CACERT $CACERT_NEW
-        CACERT=$CACERT_NEW
+        JRE_CACERTS_PATH_NEW=$(mktemp)
+        echo "Using a temporary truststore at $JRE_CACERTS_PATH_NEW"
+        cp "$JRE_CACERTS_PATH" "$JRE_CACERTS_PATH_NEW"
+        JRE_CACERTS_PATH=$JRE_CACERTS_PATH_NEW
         # If we use a custom truststore, we need to make sure that the JVM uses it
-        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${CACERT} -Djavax.net.ssl.trustStorePassword=changeit"
+        export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -Djavax.net.ssl.trustStore=${JRE_CACERTS_PATH} -Djavax.net.ssl.trustStorePassword=changeit"
     fi
 
     tmp_store=$(mktemp)
@@ -37,14 +41,17 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
     trust extract --overwrite --format=java-cacerts --filter=ca-anchors --purpose=server-auth "$tmp_store"
 
     # Add the system CA certificates to the JVM truststore.
-    keytool -importkeystore -destkeystore "$CACERT" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt # >/dev/null
+    keytool -importkeystore -destkeystore "$JRE_CACERTS_PATH" -srckeystore "$tmp_store" -srcstorepass changeit -deststorepass changeit -noprompt
+
+    # Clean up the temporary truststore
+    rm "$tmp_store"
 
     # Import the additional certificate into JVM truststore
     for i in /certificates/*crt; do
         if [ ! -f "$i" ]; then
             continue
         fi
-        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$CACERT" -storepass changeit # >/dev/null
+        keytool -import -noprompt -alias "$(basename "$i" .crt)" -file "$i" -keystore "$JRE_CACERTS_PATH" -storepass changeit # >/dev/null
     done
 
     # Add additional certificates to the system CA store. This requires write permissions to several system
@@ -68,12 +75,12 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
         fi
 
         # UBI/CentOS
-        if which update-ca-trust >/dev/null; then
+        if command -v update-ca-trust >/dev/null; then
             update-ca-trust
         fi
 
         # Ubuntu/Alpine
-        if which update-ca-certificates >/dev/null; then
+        if command -v update-ca-certificates >/dev/null; then
             update-ca-certificates
         fi
     else
@@ -84,6 +91,6 @@ if [ -n "$USE_SYSTEM_CA_CERTS" ]; then
 fi
 
 # Let's provide a variable with the correct path for tools that want or need to use it
-export CACERT
+export JRE_CACERTS_PATH
 
 exec "$@"
diff --git a/docker_templates/ubuntu.Dockerfile.j2 b/docker_templates/ubuntu.Dockerfile.j2
index 05dac147a..a74e892a6 100644
--- a/docker_templates/ubuntu.Dockerfile.j2
+++ b/docker_templates/ubuntu.Dockerfile.j2
@@ -43,5 +43,5 @@ ENV JAVA_VERSION {{ java_version }}
 {% endif %}
 {% include 'partials/version-check.j2' %}
 COPY entrypoint.sh /__cacert_entrypoint.sh
-ENTRYPOINT ["/__cacert_entrypoint.sh"]
-{% include 'partials/jshell.j2' %}
\ No newline at end of file
+ENTRYPOINT ["{{ shebang }}", "/__cacert_entrypoint.sh"]
+{% include 'partials/jshell.j2' %}
diff --git a/generate_dockerfiles.py b/generate_dockerfiles.py
index 5c786bebf..4890dbe7d 100644
--- a/generate_dockerfiles.py
+++ b/generate_dockerfiles.py
@@ -54,6 +54,7 @@ def archHelper(arch, os_name):
         directory = configuration["directory"]
         architectures = configuration["architectures"]
         os_name = configuration["os"]
+        shebang = configuration.get("shebang", "")
         base_image = configuration["image"]
         deprecated = configuration.get("deprecated", None)
         versions = configuration.get(
@@ -140,6 +141,7 @@ def archHelper(arch, os_name):
                     arch_data=arch_data,
                     os_family=os_family,
                     os=os_name,
+                    shebang=shebang,
                 )
 
                 print("Writing Dockerfile to", output_directory)