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Kotlin Scripting Examples: kotlin-main-kts usages

Scripts demonstrating the usage of the kotlin-main-kts script definition jar, distributed with the Kotlin compiler and the IntelliJ plugin.

See also simplified implementation in this repository

Description

The purpose of the main-kts is to allow writing simple but extendable utility scripts for the usage in the command line, replacing the simple Kotlin programs with main function (hence the main in its name).

Usage

For example a script (note that the file should have an extension corresponding to the script definition, in this case .main.kts):

println("Hello, ${args[0]}")

could be executed with the command

kotlinc -cp <path/to/kotlin-main-kts.jar> script.main.kts

and starting from Kotlin version 1.3.70 it could even be used without explicit kotlin-main-kts.jar in the classpath, provided that the compiler could find the required jars. In addition starting from 1.3.70 kotlin runner supports scripts the same way as kotlinc -script combination:

kotlin script.main.kts

or even as simple as

./script.main.kts

provided that the shebang line is added to the script and works in the given OS shell

#!/usr/bin/env kotlin

Caching

The compiled scripts are cached to the directory defined by an environment variable KOTLIN_MAIN_KTS_COMPILED_SCRIPTS_CACHE_DIR ($TEMP/main.kts.compiled.cache by default, where TEMP is a platform specific directory for cache. For an example ~/Library/Caches on MacOS), and if the script is not changed, the compiled one is executed from the cache.

IntelliJ support

Starting from the Kotlin IntelliJ plugin version 1.3.70, the .main.kts scripts are supported automatically in the IntelliJ IDEA, provided that they are placed outside of the regular source folders. E.g. if this project is imported into the IntelliJ, the demo scripts in the scripts folders should be properly highlighted and support navigation, including navigation into imported libraries.

Demo Scripts

  • kotlinx-html.main.kts demonstrates usage of the kotlinx-html library by JetBrains, to generate HTML output

  • kotlin-shell.main.kts demonstrates usage of the kotlin-shell library by Jakub Riegel, to execute OS shell commands with easy interaction with Kotlin code and can be executed:

    • without arguments - executes "ls -l" command for curren directory
    • with argument - executes "wc" command for a file
    kotlin kotlin-shell.main.kts main-kts/example.txt

  • composite/composite.main.kts demonstrates script composition capabilities via @file:Import annotation
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