Java/Kotlin run Runtime.getRuntime().exec() with visible command prompt

Question

On my windows system, I would like to use Runtime.getRuntime().exec(command) to launch a subprocess with a python script and have the command prompt terminal open so users can see the process working. My command is something like:

val command = "cmd /c python ~path_to_file~ ~args~"

I'm aware there's an alternate method to print the contents of the command prompt back into the original terminal via something like:

import java.util.Scanner
fun main(args: Array<String>) {
    val proc = Runtime.getRuntime().exec("cmd /C dir") 
    Scanner(proc.inputStream).use {
        while (it.hasNextLine()) println(it.nextLine())
    }
}

Just wondering if there's another option I haven't seen yet.

Iaroslav Postovalov · Accepted Answer · 2020-03-20 06:53:45Z

4

I think you should use ProcessBuilder's redirecting:

fun main() {
    ProcessBuilder("cmd", "/C", "dir")
        .redirectOutput(ProcessBuilder.Redirect.INHERIT)
        .start()
        .waitFor()
}

This example has same behavior as yours.

answered Mar 20, 2020 at 6:53

Iaroslav Postovalov

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3 Comments

PeptideWitch Over a year ago

Thanks for the answer. I can replicate the same behaviour as above but there's no visible command prompt/terminal that appears to display the output. I'm fine with re-directing, but is there a way I can force open the terminal?

Iaroslav Postovalov Over a year ago

@PeptideWitch yes. Try replacing cmd /C dir with cmd /C start dir

Subramanya Rao Over a year ago

this worked for me, windows 10

kotlin ProcessBuilder("cmd /C start dir".split(" "))         .redirectOutput(ProcessBuilder.Redirect.INHERIT)         .start()         .waitFor()

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