How to execute shell command from Kotlin

In Kotlin, also we can use ProcessBuilder or Runtime.getRuntime().exec to execute external shell command :

ProcessBuilder

This class is used to create operating system processes. Each ProcessBuilder instance manages a collection of process attributes. The start() method creates a new Process instance with those attributes. The start() method can be invoked repeatedly from the same instance to create new subprocesses with identical or related attributes.

fun processBuilder() {
    val processBuilder = ProcessBuilder()
    // -- Linux --

    // Run a shell command
    //processBuilder.command("bash", "-c", "ls /home/your_user/")

    // Run a shell script
    //processBuilder.command("path/to/hello.sh");

    // -- Windows --
    // Run a command
    processBuilder.command("cmd.exe", "/c", "dir C:/Users/your_user");

    // Run a bat file
    //processBuilder.command("C:/Users/your_user/file.bat");

    try {

        val process: Process = processBuilder.start()
        val reader = BufferedReader(InputStreamReader(process.inputStream))
        val line = reader.readText();
        println(line)

        val exitVal = process.waitFor()
        if (exitVal == 0) {
            println("Success!")
            //exitProcess(0)
        } else {
            //else...
        }
    } catch (e: IOException) {
        e.printStackTrace()
    } catch (e: InterruptedException) {
        e.printStackTrace()
    }
}

Runtime.getRuntime().exec()

Every Java application has a single instance of class Runtime that allows the application to interface with the environment in which the application is running. The current runtime can be obtained from the getRuntime method.

fun runtimeExec() {

    try {
        // -- Linux --

        // Run a shell command
        //val process = Runtime.getRuntime().exec("ls /home/your_user/")

        // Run a shell script
        //val process = Runtime.getRuntime().exec("path/to/hello.sh")

        // -- Windows --

        // Run a command
        val process = Runtime.getRuntime().exec("cmd /c dir C:/Users/your_user")

        //Run a bat file
        //val process = Runtime.getRuntime().exec(
        //        "cmd /c hello.bat", null, File("C:/Users/your_user/"))

        val reader = BufferedReader(
            InputStreamReader(process.inputStream))

        val line = reader.readText();
        println(line)

        val exitVal = process.waitFor()
        if (exitVal == 0) {
            println("Success!")
            // exitProcess(0)
        } else {
            //else...
        }

    } catch (e: IOException) {
        e.printStackTrace()
    } catch (e: InterruptedException) {
        e.printStackTrace()
    }

}

Run & Test

hello.sh

#!/bin/sh

echo Hello World

fun main(args: Array<String>) {
    val processBuilder = ProcessBuilder()

    // -- Linux --
    // Run a shell command
    processBuilder.command("bash", "-c", "sh /home/hello.sh")

    try {

        val process: Process = processBuilder.start()
        val reader = BufferedReader(InputStreamReader(process.inputStream))
        val line = reader.readText();
        println(line)

        val exitVal = process.waitFor()
        if (exitVal == 0) {
            println("Success!")
            //exitProcess(0)
        } else {
            //else...
        }
    } catch (e: IOException) {
        e.printStackTrace()
    } catch (e: InterruptedException) {
        e.printStackTrace()
    }

}

Output

References:

https://mkyong.com/java/how-to-execute-shell-command-from-java/

https://docs.oracle.com/javase/7/docs/api/java/lang/ProcessBuilder.html

https://docs.oracle.com/javase/7/docs/api/java/lang/Runtime.html