A simple bash script to build and run a single kotlin file with build cache to only re compile if source file changes.

kotlinRun.sh

#!/bin/bash
#
# A simple bash script to build and run a single kotlin file
# with build cache to only re compile if source file changes
#
# Copyright (C) 2023 Joe Baker (JoeBlakeB)
# This program is free software under the GPLv3 license.
#

if [[ $1 == "-h" || $1 == "--help" ]]; then
    echo "Usage: kotlinRun filename [buildpath]"
    echo "filename  The kotlin file you want to run"
    echo "buildpath Where you want the build files to be stored"
    exit 0
fi

if [ -z "$1" ]; then
    echo "Error: filename argument is required."
    exit 1
fi

filename="$1"
buildpath="${2:-./build/}"

if [ ! -f "$filename" ]; then
    echo "Error: $filename not found"
    exit 1
fi

if [[ ! "$buildpath" == */ ]]; then
    buildpath="$buildpath/"
fi

mkdir -p "$buildpath"

# Check the files hash against last time it was built

currentHash=$(sha256sum "$filename")

if [ -f "$buildpath$filename".txt ] && [ -f "$buildpath$filename".jar ]; then
    previousHash=$(cat "$buildpath$filename".txt)
fi

# Recompile kotlin file if needed, then run

if [ ! "$currentHash" == "$previousHash" ]; then
    kotlinc "$filename" -include-runtime -d "$buildpath$filename".jar
    exitCode=$?
    if [ ! $exitCode -eq 0 ]; then
        echo "Error: kotlinc failed to compile $filename"
        rm "$buildpath$filename".jar
        exit $exitCode
    fi
    echo -n "$currentHash" > "$buildpath$filename".txt
fi

java -jar "$buildpath$filename".jar