title: maven exec plugin exception
body: <p>I am getting following exception. How do I know which command is failing and why?</p>
  
  <pre><code>[ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.2.1:exec (XYZ) on project ABC: Command execution failed. Process exited with an error: 127 (Exit value: 127) -&gt; [Help 1]
  org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.2.1:exec (XYZ) on project ABC: Command execution failed.
      at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:216)
      at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
      at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
      at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:108)
      at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:76)
      at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
      at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:116)
      at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:361)
      at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:155)
      at org.apache.maven.cli.MavenCli.execute(MavenCli.java:584)
      at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:213)
      at org.apache.maven.cli.MavenCli.main(MavenCli.java:157)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:497)
      at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
      at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
      at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
      at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
  Caused by: org.apache.maven.plugin.MojoExecutionException: Command execution failed.
      at org.codehaus.mojo.exec.ExecMojo.execute(ExecMojo.java:362)
      at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:133)
      at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:208)
      ... 19 more
  Caused by: org.apache.commons.exec.ExecuteException: Process exited with an error: 127 (Exit value: 127)
      at org.apache.commons.exec.DefaultExecutor.executeInternal(DefaultExecutor.java:377)
      at org.apache.commons.exec.DefaultExecutor.execute(DefaultExecutor.java:160)
      at org.codehaus.mojo.exec.ExecMojo.executeCommandLine(ExecMojo.java:610)
      at org.codehaus.mojo.exec.ExecMojo.execute(ExecMojo.java:352)
      ... 21 more
  </code></pre>