Changes to add a bash magic

docs/magics.md

@@ -124,4 +124,31 @@ The cell magic is designed to make it very simple to copy and paste from any REA
       <artifactId>jupyter-jvm-basekernel</artifactId>
       <version>2.0.0-SNAPSHOT</version>
     </dependency>
-    ```
+    ```
+
+
+### bash
+
+Runs a shell command and show the output
+
+###### Line magic
+
+*   **arguments**:
+    *   command and list of arguments of the command
+
+    Ex: To get a resource from an URL and save to a file in `/tmp`
+
+    ```
+    %bash wget URL -O /tmp/file
+    ```
+
+    Ex: to list files in a folder
+    ```
+    %bash ls folder
+    ```
+
+    This can be integrated with other Java sentences:
+    ```java
+    System.out.println("Contents of folder:");
+    %bash ls folder
+    ```

src/main/java/io/github/spencerpark/ijava/JavaKernel.java

@@ -26,6 +26,7 @@
 import io.github.spencerpark.ijava.execution.*;
 import io.github.spencerpark.ijava.magics.ClasspathMagics;
 import io.github.spencerpark.ijava.magics.MavenResolver;
+import io.github.spencerpark.ijava.magics.BashMagics;
 import io.github.spencerpark.jupyter.kernel.BaseKernel;
 import io.github.spencerpark.jupyter.kernel.LanguageInfo;
 import io.github.spencerpark.jupyter.kernel.ReplacementOptions;
@@ -95,6 +96,7 @@ public JavaKernel() {
         this.magics.registerMagics(this.mavenResolver);
         this.magics.registerMagics(new ClasspathMagics(this::addToClasspath));
         this.magics.registerMagics(new Load(List.of(".jsh", ".jshell", ".java", ".ijava"), this::eval));
+        this.magics.registerMagics(new BashMagics());
 
         this.languageInfo = new LanguageInfo.Builder("Java")
                 .version(Runtime.version().toString())

src/main/java/io/github/spencerpark/ijava/magics/BashMagics.java

@@ -0,0 +1,30 @@
+
+package io.github.spencerpark.ijava.magics;
+
+import io.github.spencerpark.jupyter.kernel.magic.registry.LineMagic;
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.List;
+
+public class BashMagics {
+
+   @LineMagic(aliases={"bash","shell"})
+   public void bash(List<String> args) {
+      ProcessBuilder pb = new ProcessBuilder(args);
+      StringBuffer sb = new StringBuffer();
+      try {
+         Process p = pb.start();
+         BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream(), "UTF-8"));
+         p.waitFor();
+         String cad = "";
+         while ((cad = br.readLine()) != null){
+            sb.append(cad);
+            sb.append('\n');
+         }
+         br.close();
+      } catch (Exception ex) {
+         ex.printStackTrace();
+      }
+      System.out.println(sb.toString());
+   }
+}