How to both capture shell command output AND show it in terminal at realtime?

Question

I wrote a function, which runs external commands and captures their outputs, something like this

    proc = subprocess.run(command_line, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    if proc.returncode != 0:

Unfortunately, I don't see long commands output as they running. How to do this conditionally, for example, if loglevel is debug or higher?

I am not sure what are you asking. Do you want to have a "debug mode" that prints the output on the terminal? — alec_djinn, Oct 09 '19 at 11:06
Yes, something like this. I want to control, either print output or not, but capture it always — Dims, Oct 09 '19 at 11:24
Have you considered using `check_output()` instead of `run()`? — alec_djinn, Oct 09 '19 at 11:28
output = check_output(...). The you can print it or not as you want — alec_djinn, Oct 09 '19 at 11:33
This will be possible only when command is finished, while I wish to print output during the way — Dims, Oct 09 '19 at 11:34
Yes, this can work only after the command is executed till completion. — alec_djinn, Oct 09 '19 at 11:35
This may help. http://stackoverflow.com/questions/418896/ddg#418899 — alec_djinn, Oct 09 '19 at 11:41
Also this https://stackoverflow.com/questions/14906764/how-to-redirect-stdout-to-both-file-and-console-with-scripting — alec_djinn, Oct 09 '19 at 11:47

score 0 · Answer 1 · answered Oct 09 '19 at 11:05

This code will print the command output as soon as it is received:

import sys
import subprocess
try:
    proc = subprocess.Popen(
        command,
        stdout=subprocess.PIPE,
        shell=shell)
except OSError as e:
    print('Error executing command', command, e)
    raise
for stdout_line in iter(proc.stdout.readline, b''):
    sys.stdout.write(stdout_line)
    sys.stdout.flush()
proc.stdout.close()

How to both capture shell command output AND show it in terminal at realtime?

1 Answers1