Executing shell commands and getting output in gradle

executeShellInGradle

def getVersionName = { ->
    def hashStdOut = new ByteArrayOutputStream()
    exec {
        commandLine "git", "rev-parse", "--short", "HEAD"
        standardOutput = hashStdOut
    }
 
    def buildNumberStdOut = new ByteArrayOutputStream()
    exec {
        commandLine 'echo', "$BUILD_NUMBER"
        standardOutput = buildNumberStdOut
    }
    return buildNumberStdOut.toString().trim() + '-' + hashStdOut.toString().trim()
}
 
def getVersionName2() {
    return "echo $BUILD_NUMBER".execute().text.trim() +
            "-" +
            "git rev-parse --short HEAD".execute().text.trim()
}
 
 
task printGitVersionName {
    doLast {
        println getVersionName()
        println getVersionName2()
    }
}

// execute as "./gradlew -q printGitVersionName -PBUILD_NUMBER=457"