How Can I Capture the Output of Shell Commands in Python?

Capturing Output of Shell Commands

When executing shell commands, it's often necessary to capture their output, whether error or success messages. Here are some approaches to achieve this:

Python 3.5

run function:

import subprocess

result = subprocess.run(['ls', '-l'], stdout=subprocess.PIPE)
output = result.stdout.decode('utf-8')

One-liner for Python 3.7 :

subprocess.run(['ls', '-l'], capture_output=True, text=True).stdout

Python 2.7

check_output function:

import subprocess

output = subprocess.check_output(['mysqladmin', 'create', 'test', '-uroot', '-pmysqladmin12'])
output = output.decode('utf-8')

Popen** for Advanced Cases

import subprocess

p = subprocess.Popen(['ls', '-a'], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
output, error = p.communicate()
output = output.decode('utf-8')
if error:
    error = error.decode('utf-8')

Notes

• shell=True: Use this argument with caution, as it raises security concerns by allowing the execution of arbitrary shell commands.
• communicate: Use communicate to capture output and optionally send input.
• Pipes: Avoid directly connecting pipes. Consider executing commands separately and passing output between them.

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