antExec – Executing external processes in Groovy

Groovy is a nice language. I currently use it for writing maven plugins and for doing scripting tasks in the realm of build automation.

Poor mans integration with .NET or other systems is the command-line. Groovy has built-in support for that:


And if you need parameters:

["cmd", "/C", "cd"].execute()

But there are some problems with how to wait for the process and retrieve the streams. Often you just want the output back – and you want to make sure that the command exited with no error.

There is also a ant-integration in groovy. So I wrote a little wrapper that makes using ant’s exec-task feasible:

mixinAntExec() // has to be called once
// prints the stdout
// if the error code is != 0, 
// it throws an exeption with 
// helpful information
println ("myprog".antExec())

def result = ["myprog", "/fail"].antExec(false)
println (result.exitValue) // error code
println (result.error) // err out
println (result.text) // std out

This script can either be pasted to the bottom, or included on the script path:

def mixinAntExec() {
    String.metaClass.antExec = {failOnError=true -> antExec([delegate], failOnError)}
    ArrayList.metaClass.antExec << {failOnError=true -> antExec(delegate, failOnError)}

def antExec(command, failOnError=true) {
    def commandLiteral = command.collect{it.contains(' ') ? '"' + it + '"' : it}.join(' ')
    println "ant exec with: ${commandLiteral}"
    def ant = new AntBuilder()
             errorproperty: "error",
             resultproperty: "exitValue",
             failonerror: false,
             executable: command[0]) {
               if (command.size()>1)
                   arg(line:command[1..-1].collect{it.contains(' ') ? '"' + it + '"' : it}.join(' '))
     def result = new Expando(
         exitValue: as Integer,
         toString: {text}
     if (failOnError && result.exitValue != 0){
         throw new Exception("""command failed with ${result.exitValue}
executed: ${commandLiteral}
error: ${result.error}
text: ${result.text}""")

     return result

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