Small improvements to the install-procedure

It's now possible to run a single install-part using install.sh (instead
of calling it directly, which only works for a small number of the parts
due to them relying on variables set by install.sh).

On Ubuntu 22.04, "50-landscape-sysinfo" went from an actual file to a
symlink, so "chmod -x" wasn't effective anymore.

install/README.md

@@ -13,12 +13,17 @@ Run `📄 install.sh` to setup [`📂 .bashrc.d`](../.bashrc.d/), create various
 configuration file symlinks, and make some further
 [configuration changes](#configuration-changes).
 
-`📄 install.sh` Runs all executable files in [`📂 install/parts.d`](./parts.d/).
-To enable/disable parts of the installation, simply `chmod +x/-x` the scripts in
+`📄 install.sh` Runs all executable files in [`📂 parts.d`](./parts.d/). To
+enable/disable parts of the installation, simply `chmod +x/-x` the scripts in
 question prior to running the installer.
 
-The scripts in `📂 install/parts.d` are idempotent. They can be run multiple
-times on an already "installed" system without nasty side-effects.
+It is possible to run a _single_ part by using `install.sh <part>` (e.g.
+`install.sh 20-home` would execute [`📄 parts.d/20-home`](./parts.d/20-home)).
+This is the preferred way of running single parts on-demand – most of them
+depend on variables set by `install.sh` and thus cannot be run directly.
+
+The scripts in `📂 parts.d` are idempotent. They can be run multiple times on an
+already "installed" system without nasty side-effects.
 
 During installation, `📄 ~/.env` is created from
 [a defaults file](./../.env.default) which lists all possible environment
@@ -53,7 +58,6 @@ To pull down a non-predefined version of the tool, do:
 
 ```shell
 version=v1.24 ./powerline-go
-
 ```
 
 ### Configuration changes

install/install.sh

@@ -8,8 +8,10 @@ base=$(dirname "$(realpath "$(dirname "${BASH_SOURCE[0]}")")")
 
 for file in "$base"/install/parts.d/**; do
 
-  if [[ -x "$file" ]]; then
-    echo Installing 📄 "$(basename "$file")"...
+  file_basename="$(basename "$file")"
+
+  if [[ -x $file && (! -v 1 || $1 == "$file_basename") ]]; then
+    echo Installing 📄 "$file_basename"...
     source "$file"
   fi
 

install/parts.d/90-motd

@@ -1,7 +1,13 @@
 #!/usr/bin/env bash
 
 sudo chmod --silent -x /etc/update-motd.d/10-help-text || true
-sudo chmod --silent -x /etc/update-motd.d/50-landscape-sysinfo || true
+
+landscape_sysinfo=/etc/update-motd.d/50-landscape-sysinfo
+if [ -L "$landscape_sysinfo" ]; then
+  sudo rm "$landscape_sysinfo"
+elif [ -f "$landscape_sysinfo" ]; then
+  sudo chmod --silent -x "$landscape_sysinfo"
+fi
 
 if systemctl list-unit-files motd-news.service &> /dev/null; then
   sudo systemctl mask motd-news.service || true