Check command exists or not in Gradle.

build.gradle

task checkCommand{
    doLast{
        def result = exec{
            def command = "command -v docker"
            ignoreExitValue = true
            executable "bash" args "-l", "-c", command
        }
        if(result.getExitValue()==0){
            println "Has Docker"
        }else{
            print "No Docker"
        }
    }
}