Subprocesses: Collecting output
We don't often write programs in isolation. In a lot of cases we want to interact with the outside system and spawning a subprocess is a common way to do this.
The Deno namespace has a unified api for interacting with the outside system called Deno.Command. With it, we can initialize some information about the command but it will not be executed immediately.
const command = new Deno.Command("deno", {
args: [
"eval",
"\
console.log('hello from deno'); \
console.error('hello from stderr'); \
",
],
});In the most simple case we just want to run the process to completion. This can be achieved using command.output()
let result = await command.output();It can also be achieved synchronously using command.outputSync()
result = command.outputSync();We can now interact with stdout and stderr
const textDecoder = new TextDecoder();
console.log("stdout:", textDecoder.decode(result.stdout));
console.log("stderr:", textDecoder.decode(result.stderr));Run this example locally using the Deno CLI:
deno run --allow-run https://docs.deno.com/examples/scripts/subprocesses_output.ts