How to run execute string as a shell command in Kotlin DSL?

Help/Discuss
#1

I’m migrating to Kotlin DSL.
The old commands look like:

final gitBranch = "git rev-parse --abbrev-ref HEAD".execute().text.trim()
final gitTag = "git tag -l --points-at HEAD".execute().text.trim()
final gitCommitId = "git rev-parse --short=8 HEAD".execute().text.trim()

In Kotlin DSL i have not found the same way.
Tried this approach:https://stackoverflow.com/questions/35421699/how-to-invoke-external-command-from-within-kotlin-code

but is there is any built-in way?

#2

Perhaps the kotlin equivalent of

project.exec {
   commandLine = "git rev-parse --abbrev-ref HEAD".split(" ")
}
#3

But how than i capture the output?

#4

String.execute() is a groovy enhancement which is why it’s not available in Kotlin. It has nothing to do with Gradle. See Groovy String Enhancements

But how than i capture the output?

See Project.exec(ExecSpec)

Eg:

ByteArrayOutputStream byteOut = new ByteArrayOutputStream() 
project.exec {
   commandLine = "git rev-parse --abbrev-ref HEAD".split(" ")
   standardOutput = byteOut
} 
String output = new String(byteOut.toByteArray())
#5

I hoped to have smth shorter ((. Than i’d better introduce a function, like in this answer:

fun String.runCommand(workingDir: File = file("./")): String {
    val parts = this.split("\\s".toRegex())
    val proc = ProcessBuilder(*parts.toTypedArray())
            .directory(workingDir)
            .redirectOutput(ProcessBuilder.Redirect.PIPE)
            .redirectError(ProcessBuilder.Redirect.PIPE)
            .start()

    proc.waitFor(1, TimeUnit.MINUTES)
    return proc.inputStream.bufferedReader().readText().trim()
}
#6

I’d use project.exec rather than ProcessBuilder directly. I’m sure there’s some nice error handling etc in the Gradle version

#7

unfortunately i’ve not understood how to use that code snippe with project.exec. Shall i repeat all these 5 lines for each command i want to execute?

with ProcessBuilder i declare fun runCommand once and reuse it in the build script:

fun String.runCommand(workingDir: File = file("./")): String {
    val parts = this.split("\\s".toRegex())
    val proc = ProcessBuilder(*parts.toTypedArray())
            .directory(workingDir)
            .redirectOutput(ProcessBuilder.Redirect.PIPE)
            .redirectError(ProcessBuilder.Redirect.PIPE)
            .start()

    proc.waitFor(1, TimeUnit.MINUTES)
    return proc.inputStream.bufferedReader().readText().trim()
}

val gitBranch = "git rev-parse --abbrev-ref HEAD".runCommand()
val gitTag = "git tag -l --points-at HEAD".runCommand()
val gitCommitId = "git rev-parse --short=8 HEAD".runCommand()
#9

Here’s what it might look like in groovy

def runCommand = { Project project, String command ->
   ByteArrayOutputStream byteOut = new 
   ByteArrayOutputStream() 
   project.exec {
      commandLine = command.split(" ")
      standardOutput = byteOut
   } 
   return new String(byteOut.toByteArray()).trim()
}
def gitBranch = runCommand(project, "git rev-parse --abbrev-ref HEAD") 
def gitTag = runCommand(project, "git tag -l --points-at HEAD") 
def gitCommitId = runCommand(project, "git rev-parse --short=8 HEAD")
1 Like
#10

ok, for Kotlin DSL it looks like this:

fun String.runCommand(currentWorkingDir: File = file("./")): String {
    val byteOut = ByteArrayOutputStream()
    project.exec {
        workingDir = currentWorkingDir
        commandLine = this@runCommand.split("\\s".toRegex())
        standardOutput = byteOut
    }
    return String(byteOut.toByteArray()).trim()
}

val gitBranch = "git branch --show-current".runCommand()
val gitTag = "git tag -l --points-at HEAD".runCommand()
val gitCommitId = "git rev-parse HEAD".runCommand()
1 Like
#11

There is a kotlin library for easy run external command

Add this gradle dependency:

implementation("com.sealwu:kscript-tools:1.0.1")

And can run comamnd like this:

"cd ~ && ls".runCommand()

Output:

Applications   Downloads      MavenDep       Pictures       iOSProjects
Desktop        IdeaProjects   Movies         Public         scripts
Documents      Library        Music          StudioProjects

Also you can get the output of command line by using evalBash

val date = "date".evalBash().getOrThrow()  //execute shell command `date` and get the command's output and set the content to date variable
println(date) //This will print Fri Aug 19 21:59:56 CEST 2022 on console
val year = date.substringAfterLast(" ") // will get 2022 and assign to 
println(year)

Output:

Fri Aug 19 21:59:56 CEST 2022
2022
#12

And still you shouldn’t use it, but should use Exec task or exec methods to call external processes in the Gradle context. :wink: