caching output?

[loynoir]

If there's a time consuming command,

• want real time output to console
• want capture final output

Something similar to shell

ret=$(bash -c 'echo 1; sleep 2; echo 2'|tee /dev/stderr)

Currently I use

    p.stdout?.pipe(process.stdout)
    p.stderr?.pipe(process.stderr)
    await p.then(p => ret = p)

[ehmicky]

Hi @loynoir,

Yes, this is the recommended way. The following documentation section describes it.
Please note the last line of your example can be reduced to const ret = await p.

[loynoir]

Oh, I know why, I tried it first in REPL, and use a small gap.

Seems execa is not caching output.

> p=execa('bash',['-c','echo a; sleep 2; echo b']);void p.stdout.pipe(process.stdout)
... 3 seconds later ...
> ret=await p
> ret.stdout
''

[ehmicky]

Execa is caching/buffering the output, but only after the promise returned by execa() has been followed (which you do with await in your code above).

The example in the documentation is not meant for the REPL. In the REPL, to avoid the small delay you're mentioning, you need to enter all statements at once:

> const childProcess = execa('bash', ['-c', 'echo a; sleep 2; echo b']); childProcess.stdout.pipe(process.stdout); const { stdout } = await childProcess; 
> stdout;
'a\nb'

[loynoir]

Thanks for your answer 😃