Kotlin-native execute command and get the output

Question

I'd like to know if there's a way in kotlin native to call a command via posix and receive it's terminal output. For example, I'd like to get the "git diff" command working without having to create a temporary file, write output to it and then read from that file.

On SO I've only found solutions requiring ProcessBuilder, which isn't available on kotlin-native, as it's a Java library.

Answer 1

It's an improved version of exec command for Kotlin Native posted by mg-lolenstine, it throws an exception with command stderr instead of just returning exit(1) (which not always desirable behavior itself), also trim is now optional

import kotlinx.cinterop.*
import platform.posix.*

fun executeCommand(
    command: String,
    trim: Boolean = true,
    redirectStderr: Boolean = true
): String {
    val commandToExecute = if (redirectStderr) "$command 2>&1" else command
    val fp = popen(commandToExecute, "r") ?: error("Failed to run command: $command")

    val stdout = buildString {
        val buffer = ByteArray(4096)
        while (true) {
            val input = fgets(buffer.refTo(0), buffer.size, fp) ?: break
            append(input.toKString())
        }
    }

    val status = pclose(fp)
    if (status != 0) {
        error("Command `$command` failed with status $status${if (redirectStderr) ": $stdout" else ""}")
    }

    return if (trim) stdout.trim() else stdout
}