I have a python script with the following code:
print("Hello Deno")
I want to run this python script (test.py) from test.ts using Deno. This is the code in test.ts so far:
const cmd = Deno.run({cmd: ["python3", "test.py"]});
How can I get the output, of the python script in Deno?
To execute a python script from Deno you need to use Deno.Command
const command = new Deno.Command('python3', {
args: [ "test.py" ],
});
const { code, stdout, stderr } = await command.output();
console.log(new TextDecoder().decode(stdout));
console.log(new TextDecoder().decode(stderr));
Old answer: Deno.run is now deprecated in favor of Deno.Command
Deno.run returns an instance of Deno.Process. In order to get the output use .output(). Don't forget to pass stdout/stderr options if you want to read the contents.
// --allow-run
const cmd = Deno.run({
cmd: ["python3", "test.py"],
stdout: "piped",
stderr: "piped"
});
const output = await cmd.output() // "piped" must be set
const outStr = new TextDecoder().decode(output);
const error = await cmd.stderrOutput();
const errorStr = new TextDecoder().decode(error);
cmd.close(); // Don't forget to close it
console.log(outStr, errorStr);
If you don't pass stdout property you'll get the output directly to stdout
const p = Deno.run({
cmd: ["python3", "test.py"]
});
await p.status();
// output to stdout "Hello Deno"
// calling p.output() will result in an Error
p.close()
You can also send the output to a File
// --allow-run --allow-read --allow-write
const filepath = "/tmp/output";
const file = await Deno.open(filepath, {
create: true,
write: true
});
const p = Deno.run({
cmd: ["python3", "test.py"],
stdout: file.rid,
stderr: file.rid // you can use different file for stderr
});
await p.status();
p.close();
file.close();
const fileContents = await Deno.readFile(filepath);
const text = new TextDecoder().decode(fileContents);
console.log(text)
In order to check status code of the process you need to use .status()
const status = await cmd.status()
// { success: true, code: 0, signal: undefined }
// { success: false, code: number, signal: number }
In case you need to write data to stdin you can do it like this:
const p = Deno.run({
cmd: ["python", "-c", "import sys; assert 'foo' == sys.stdin.read();"],
stdin: "piped",
});
// send other value for different status code
const msg = new TextEncoder().encode("foo");
const n = await p.stdin.write(msg);
p.stdin.close()
const status = await p.status();
p.close()
console.log(status)
You'll need to run Deno with: --allow-run flag in order to use Deno.run
