modify-subprocess-stdout.py

import sys
import subprocess


def execute_subprocess(command):
    process = subprocess.Popen(command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)

    while True:
        line = process.stdout.readline()
        if line:
            yield line
        if not line and process.poll() is not None:
            break


if __name__ == '__main__':
    command = 'ls -l'
    prefix = 'INFO'

    for line in execute_subprocess(command=command):
        log_output = "[{}] {}".format(prefix, line.decode('utf8'))
        sys.stdout.write(log_output)

• This is the example code to execute ls -l command with subprocess.

• Sample output that adds [INFO] to the stdout:

# python  modify-subprocess-stdout.py
[INFO] total 40
[INFO] -rw-r--r--  1 root root 1090 Feb 21 03:27 Dockerfile
[INFO] -rw-r--r--  1 root root 1573 Feb 21 03:27 README.md
[INFO] drwxr-xr-x  7 root root  224 Feb 27 06:54 app
[INFO] drwxr-xr-x  8 root root  256 Feb 27 16:39 config