// Created on savesnippets.com · https://savesnippets.com/desPJGTmOCRm3k import java.io.File fun main() { val log = File("/tmp/app.log") // Whole text in one go log.writeText("startup at ${System.currentTimeMillis()}\n") // Append individual lines log.appendText("user signed in\n") log.appendText("user signed out\n") // For many writes — buffer + auto-close via `use { }` log.bufferedWriter().use { w -> repeat(10) { i -> w.write("line $i") w.newLine() } } // Atomic write (rename pattern): write to .tmp, then rename val tmp = File("/tmp/state.json.tmp") val target = File("/tmp/state.json") tmp.writeText("""{"ready": true}""") tmp.renameTo(target) }