For CLI tools, it's often useful to read from stdin. In Bun, the console object is an AsyncIterable that yields lines from stdin.
index.ts
const prompt = "Type something: ";
process.stdout.write(prompt);
for await (const line of console) {
console.log(`You typed: ${line}`);
process.stdout.write(prompt);
}
Running this file results in a never-ending interactive prompt that echoes whatever the user types.
bun run index.tsType something: hello
You typed: hello
Type something: hello again
You typed: hello againBun also exposes stdin as a BunFile via Bun.stdin. This is useful for incrementally reading large inputs that are piped into the bun process.
There is no guarantee that the chunks will be split line-by-line.
stdin.ts
for await (const chunk of Bun.stdin.stream()) {
// chunk is Uint8Array
// this converts it to text (assumes ASCII encoding)
const chunkText = Buffer.from(chunk).toString();
console.log(`Chunk: ${chunkText}`);
}
This will print the input that is piped into the bun process.
echo "hello" | bun run stdin.tsChunk: helloSee Docs > API > Utils for more useful utilities.