我如何将 shell 命令 output 存储到 python 中的变量？

Question

Code:

# cat mylinux.py
# This program is to interact with Linux

import os

v = os.system("cat /etc/redhat-release")

Output:

# python mylinux.py
Red Hat Enterprise Linux Server release 7.6 (Maipo)

In the above output, the command output is displayed regardless of the variable I defined to store the output.

How to store the shell command output to a variable using os.system method only?

Answer 1

By using module subprocess . It is included in Python's standard library and aims to be the substitute of os.system . (Note that the parameter capture_output of subprocess.run was introduced in Python 3.7)

>>> import subprocess
>>> subprocess.run(['cat', '/etc/hostname'], capture_output=True)
CompletedProcess(args=['cat', '/etc/hostname'], returncode=0, stdout='example.com\n', stderr=b'')
>>> subprocess.run(['cat', '/etc/hostname'], capture_output=True).stdout.decode()
'example.com\n'

In your case, just:

import subprocess

v = subprocess.run(['cat', '/etc/redhat-release'], capture_output=True).stdout.decode()

Update: you can split the shell command easily with shlex.split provided by the standard library.

>>> import shlex
>>> shlex.split('cat /etc/redhat-release')
['cat', '/etc/redhat-release']
>>> subprocess.run(shlex.split('cat /etc/hostname'), capture_output=True).stdout.decode()
'example.com\n'

Update 2: os.popen mentioned by @Matthias

However, is is impossible for this function to separate stdout and stderr.

import os

v = os.popen('cat /etc/redhat-release').read()