Python Script execute commands in Terminal

Question

I read this somewhere a while ago but cant seem to find it. I am trying to find a command that will execute commands in the terminal and then output the result.

For example: the script will be:

command 'ls -l'

It will out the result of running that command in the terminal

Answer 1

There are several ways to do this:

A simple way is using the os module:

import os
os.system("ls -l")

More complex things can be achieved with the subprocess module: for example:

import subprocess
test = subprocess.Popen(["ping","-W","2","-c", "1", "192.168.1.70"], stdout=subprocess.PIPE)
output = test.communicate()[0]

Answer 2

I prefer usage of subprocess module:

from subprocess import call
call(["ls", "-l"])

Reason is that if you want to pass some variable in the script this gives very easy way for example take the following part of the code

abc = a.c
call(["vim", abc])

Answer 3

import os
os.system("echo 'hello world'")

This should work. I do not know how to print the output into the python Shell.

Answer 4

• Custom standard input for python subprocess

In fact any question on subprocess will be a good read

• https://stackoverflow.com/questions/tagged/subprocess

Answer 5

for python3 use subprocess

import subprocess
s = subprocess.getstatusoutput(f'ps -ef | grep python3')
print(s)

You can also check for errors:

import subprocess
s = subprocess.getstatusoutput('ls')
if s[0] == 0:
    print(s[1])
else:
    print('Custom Error {}'.format(s[1]))


# >>> Applications
# >>> Desktop
# >>> Documents
# >>> Downloads
# >>> Library
# >>> Movies
# >>> Music
# >>> Pictures

import subprocess
s = subprocess.getstatusoutput('lr')
if s[0] == 0:
    print(s[1])
else:
    print('Custom Error: {}'.format(s[1]))

# >>> Custom Error: /bin/sh: lr: command not found

Answer 6

You should also look into commands.getstatusoutput

This returns a tuple of length 2.. The first is the return integer (0 - when the commands is successful) second is the whole output as will be shown in the terminal.

For ls

import commands
s = commands.getstatusoutput('ls')
print s
>> (0, 'file_1\nfile_2\nfile_3')
s[1].split("\n")
>> ['file_1', 'file_2', 'file_3']

Answer 7

In python3 the standard way is to use subprocess.run

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

Answer 8

The os.popen() is pretty simply to use, but it has been deprecated since Python 2.6. You should use the subprocess module instead.

Read here: reading a os.popen(command) into a string

Answer 9

Jupyter

In a jupyter notebook you can use the magic function !

!echo "execute a command"
files = !ls -a /data/dir/ #get the output into a variable

ipython

To execute this as a .py script you would need to use ipython

files = get_ipython().getoutput('ls -a /data/dir/')

execute script

$ ipython my_script.py

Answer 10

You could import the 'os' module and use it like this :

import os
os.system('#DesiredAction')

Answer 11

• Running: subprocess.run
• Output: subprocess.PIPE
• Error: raise RuntimeError

---

#! /usr/bin/env python3
import subprocess


def runCommand (command):
    output=subprocess.run(
        command,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE)

    if output.returncode != 0:
        raise RuntimeError(
            output.stderr.decode("utf-8"))

    return output


output = runCommand ([command, arguments])
print (output.stdout.decode("utf-8"))