exec-maven-plugin says cannot run specified program, even though it is on the PATH

Question

Edit 20140716:

Solution found

tl;dr = exec-maven-plugin does not recognise .cmd files, but only .bat files, as executable scripts. Rename grunt.cmd --> grunt.bat, bower.cmd --> bower.bat, etc. as a workaround.

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Having done npm install -g grunt-cli on my system, grunt is most certainly on the PATH

When I run maven install however, this doesn't seem to register.

    [ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.2.1:exec 
    (build-spa-bower) on project foobar: Command execution failed. 
    Cannot run program "grunt" (in directory "C:\workspace\foobar\src\main\spa"): 
    CreateProcess error=2, The system cannot find the file specified -> [Help 1]
    org.apache.maven.lifecycle.LifecycleExecutionException: 
    Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.2.1:exec 
    (build-spa-bower) on project foobar: Command execution failed.

Just to be sure, in the same terminal, I have executed this

cd C:\workspace\foobar\src\main\spa
grunt build

... in the same terminal as I issued the maven command above, and grunt executes just fine.

Does exec-maven-plugin use the PATH environment variable, or does it need to be told that this executable exisst in some other way?

---

EDIT:

This documentation suggests that executables on PATH should be found, so it stumps me further.

Answer 1

I dug into the source code of exec-maven-plugin and found this snippet.

From the source of ExecMojo#getExecutablePath:

    CommandLine toRet;
    if ( OS.isFamilyWindows() && exec.toLowerCase( Locale.getDefault() ).endsWith( ".bat" ) )
    {
        toRet = new CommandLine( "cmd" );
        toRet.addArgument( "/c" );
        toRet.addArgument( exec );
    }
    else
    {
        toRet = new CommandLine( exec );
    }

I compared this to another plugin that ran grunt tasks from maven, and found this

        if (isWindows()) {
            command = "cmd /c " + command;
        }

... and that worked for me. So essentially the latter worked because all commands in WIndows were prepended with cmd /c, whereas the exec-maven-plugin did not, because it only did so for file ending in .bat.

Looking in C:\Users\USER\AppData\Roaming\npm, I see:

• node_modules (folder)
• grunt (unix script file)
• grunt.cmd (windows script file)

When I rename grunt.cmd --> grunt.bat, this solves the problem, and exec-maven-plugin is able to run this command.

(this also applies to other executables created using npm install -g, such as bower and yo)

Answer 2

In addition to bguiz' answer, which would be the best solution, I've created a workaround using Maven profiles, bypassing the problem.

This is a temporary solution, until the maven-exec-plugin's bug gets fixed.

Please upvote the bug report here: http://jira.codehaus.org/browse/MEXEC-118

Edit: The bug is resolved, you can point to 1.4-SNAPSHOT to fix it.

<project>
(...)
    <profiles>
        <profile>
            <id>grunt-exec-windows</id>
            <activation>
                <os>
                    <family>Windows</family>
                </os>
            </activation>
            <build>
                <plugins>
                    <plugin>
                        <groupId>org.codehaus.mojo</groupId>
                        <artifactId>exec-maven-plugin</artifactId>
                        <version>${exec-maven-plugin.version}</version>
                        <executions>
                            <execution>
                                <id>grunt-default</id>
                                <phase>generate-resources</phase>
                                <configuration>
                                    <executable>cmd</executable>
                                    <arguments>
                                        <argument>/C</argument>
                                        <argument>grunt</argument>
                                    </arguments>
                                </configuration>
                                <goals>
                                    <goal>exec</goal>
                                </goals>
                            </execution>
                        </executions>
                    </plugin>
                </plugins>
            </build>
        </profile>
    </profiles>
</project>

Answer 3

I had the same issue with 1.5.0 of the plugin.

The cause in my case was spaces in my user name resulting in a grunt path: C:\Users\My name with spaces\AppData\Roaming\npm.

When I moved the contents of the npm directory to a path without spaces, it worked.