How to run a Kotlin.kt file from command line?


I created a simple Kotlin file, say "hello.kt":

fun main(args:Array<String>) {
  println(“hello, Kotlin!”)

How can I run it from the command line?


You can find an answer here



bash> kotlinc/bin/kotlinc-jvm -src Hello.kt -jar hello.jar
bash> java -cp “kotlinc/lib/*:hello.jar” namespace


Nope - does not work:

I want :

opt> cat hello.kts

package hello

fun main(args: Array) {
println(“Hello World!”)

opt> ./kotlinc/bin/kotlinc hello.kts -d hello.jar
hello.kts:3:10: warning: parameter ‘args’ is never used
fun main(args: Array) {
opt> java -jar hello.jar
no main manifest attribute, in hello.jar

to work. Doesn’t the novice Kotlin programmer deserve at least that? Somewhere in the sea of “hello worlds” that DO NOT WORK???


Could you please use three backticks (```) before and after code blocks to make code and console sessions more readable? Thanks.

You are compiling a Kotlin script (kts) instead of a Kotlin file (kt). Change the extension, and you will get a JAR containing class hello.HelloKt with a static main, and a manifest marking this class as the main class.

This does not mean that it will work using java -jar hello.jar. It does not work because the Kotlin run-time is not on the class path.

The easiest way is to use the kotlin command. This will add the Kotlin run-time to the class path:

kotlin -cp hello.jar hello.HelloKt

Note that kotlin hello.jar won’t work, because then the run-time is not added to the class path. I have no idea why it is not added in this case though.

If you want to run a Kotlin script directly, you have to put the body of main(...) at the top level, and use kotlinc. See Executing Kotlin scripts in command shell