How to handle Linux commands well from Python

There are many ways to handle Linux commands from Python, but the best way is to use the Popen class, which can handle standard output and standard error output structurally.

Functions that appear

Handle standard output and standard error output from Python

output.py

# -*- coding: utf-8 -*-
from __future__ import absolute_import, unicode_literals
from subprocess import PIPE, Popen


def cmdline(command):
    """
Execute a command. shell=If True, execute via the shell.
    :param command: str
    :return: Popen
    """
    return Popen(
        args=command,
        stdout=PIPE,
        stderr=PIPE,
        shell=True
    )


#Standard output
print 'Standard output:' + cmdline('date').stdout.readline()

#Standard error output
print 'Standard error output: ' + cmdline('echo 2015|xargs wc -l').stderr.readline()

Execution result

>>> python output.py
Standard output:Monday, December 7, 2015 18:47:09 JST
Standard error output: wc: 2015: open: No such file or directory

Get the latest commit hash of git

git.py

#print the latest commit hash of git
print cmdline('git log --oneline').stdout.readline()

#Print the latest commit hash from another repository
print cmdline('cd ~/pypi/cf_recommender/ && git log --oneline').stdout.readline()

Execution result

>>> python git.py
6a2ae0a xlsx update by automatic
a2febc4 update readme

Error notification in chat when standard error exists

chat.py

# -*- coding: utf-8 -*-
from __future__ import absolute_import, unicode_literals
from subprocess import PIPE, Popen


def cmdline(command):
    """
Execute a command
    :param command: str
    :return: Popen
    """
    return Popen(
        args=command,
        stdout=PIPE,
        stderr=PIPE,
        shell=True
    )


def chat(message):
    #Dummy implementation
    print 'ERROR:' + message


#Notify the error content by chat when standard error is output
cmd = [
    'python manage.py test_json',
    'python manage.py test_battle',
]

#Command execution prefix, &&Chain multiple commands with
prefix = 'cd ~/application/ && {}'

for _cmd in cmd:
    command = prefix.format(_cmd)
    p = cmdline(command)
    print 'command:' + command

    #Chat to notify when standard error is present
    errors = p.stderr.readlines()
    if errors:
        error_message = ''.join(errors)
        chat(error_message)

Execution result

command:cd ~/application/ && python manage.py test_json
ERROR:Traceback (most recent call last):
  File "manage.py", line 10, in <module>
  ...
IOError: [Errno 2] No such file or directory: u'..../test.json'

command:cd ~/application/ && python manage.py test_battle

I'm sure there are people who know more convenient ways (・ ㅂ ・) و