Guides Process & System

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 starts a never-ending interactive prompt that echoes whatever you type.

terminal

$ bun run index.ts

Type something: hello
You typed: hello
Type something: hello again
You typed: hello again

Bun also exposes stdin as a BunFile, Bun.stdin. Use it to incrementally read large inputs piped into the bun process.

Chunks aren't guaranteed to 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}`);
}

Running stdin.ts prints whatever is piped into it.

terminal

$ echo "hello" | bun run stdin.ts

Chunk: hello

See Utils for more utilities.

Spawn child process

Read to ArrayBuffer

Read from stdin

On this page