chimera: update shell command to set a proper error code on exit

Motivation:
When a single command is executed via chimera-cli the caller probably
want to get a proper error code to identify unsuccessful execution.

Modification:
Update ShellApplication#start to return error code that should be
reported on exit. Update ShellApplication#execute to return an error
code. Update ShellApplication#start to propagate the error code if
single command mode is used. Update chimera Shell to exit application
with error code returned by ShellApplication#start.

Result:
chimera errors propagated to the user shell.

Fixes: #8129
Acked-by: Lennart Sack
Target: master
Require-book: no
Require-notes: yes

Author: kofemann

modules/common-cli/src/main/java/org/dcache/util/cli/ShellApplication.java

@@ -60,8 +60,9 @@ public ShellApplication() throws Exception {
 
     /**
      * Start processing the command(s), based on the supplied arguments.
+     * @return the exit code to return to the caller.
      */
-    protected void start(Args args) throws Throwable {
+    protected int start(Args args) throws Throwable {
         if (args.hasOption("h")) {
             System.out.println("Usage: " + getCommandName() + " [-e] [-f=<file>]|[-]|[COMMAND]");
             System.out.println();
@@ -72,19 +73,22 @@ protected void start(Args args) throws Throwable {
 
         Ansi.setEnabled(isAnsiSupported);
 
+        int exitCode = 0;
         if (args.hasOption("f")) {
             try (InputStream in = new FileInputStream(args.getOption("f"))) {
                 execute(new BufferedInputStream(in), System.out, args.hasOption("e"));
             }
         } else if (args.argc() == 1 && args.argv(0).equals("-")) {
             execute(System.in, System.out, args.hasOption("e"));
         } else if (args.argc() > 0) {
-            execute(args);
+            exitCode = execute(args);
         } else if (!hasConsole) {
             execute(System.in, System.out, args.hasOption("e"));
         } else {
             console();
         }
+
+        return exitCode;
     }
 
     /**
@@ -131,13 +135,15 @@ public Object getResult() {
 
     /**
      * Executes a single command with the output being printed to the console.
+     * @return the exit code to return to the caller.
      */
-    public void execute(Args args) throws Throwable {
+    public int execute(Args args) throws Throwable {
         if (args.argc() == 0) {
-            return;
+            return 0;
         }
 
         String out;
+        int exitCode = 0;
         try {
             if (isAnsiSupported && args.argc() > 0) {
                 if (args.argv(0).equals("help")) {
@@ -158,6 +164,7 @@ public void execute(Args args) throws Throwable {
                 sb.a(help);
             }
             out = sb.toString();
+            exitCode = 1;
         } catch (CommandExitException e) {
             throw e;
         } catch (CommandPanicException e) {
@@ -168,8 +175,10 @@ public void execute(Args args) throws Throwable {
             StringWriter sw = new StringWriter();
             t.printStackTrace(new PrintWriter(sw));
             out = sb.a(sw.toString()).toString();
+            exitCode = 1;
         } catch (Exception e) {
             out = Ansi.ansi().fg(RED).a(e.getMessage()).reset().toString();
+            exitCode = 1;
         }
         if (!isNullOrEmpty(out)) {
             console.print(out);
@@ -178,6 +187,7 @@ public void execute(Args args) throws Throwable {
             }
         }
         console.flush();
+        return exitCode;
     }
 
     /**

modules/dcache-chimera/src/main/java/org/dcache/chimera/cli/Shell.java

@@ -99,7 +99,7 @@ public static void main(String[] arguments) throws Throwable {
 
         try (Shell shell = new Shell(arguments[0], arguments[1], arguments[2], arguments[3],
               arguments[4], arguments[5], arguments[6])) {
-            shell.start(args);
+            System.exit(shell.start(args));
         }
     }