if(this.args.length){
    dir = new File(this.args[0])
    if(dir.exists() && dir.directory){
        dir.eachDirRecurse{it ->
            it.listFiles().each{ f->
                if(!f.directory){
                    println f.absolutePath;
                }
            }
        }
    } else {
        println "${this.args[0]} is not a directory."
    }
} else {
    println "Use: groovy ListFile.groovy <dir>"
}