How to Execute a Program or Call a System Command in Python

Using subprocess Module

The subprocess module allows you to spawn new processes, connect to their input/output/error pipes, and obtain their return codes. See the following example:

#!/usr/bin/python3
# -*- coding: utf8 -*-

# Import module
import subprocess

subprocess.run(["ls", "-l"])

... file.txt

On Python 3.4 and earlier, use subprocess.call instead of .run.

Using os.system Method

Execute the command (a string) in a subshell. This is implemented by calling the Standard C function system(), and has the same limitations.

#!/usr/bin/python3
# -*- coding: utf8 -*-

# Import module
import os

os.system("ls -l")

... file.txt

Using subprocess.Popen Method

Execute a child program in a new process. This is intended as a replacement for os.popen, but has the downside of being slightly more complicated by virtue of being so comprehensive. For example,

#!/usr/bin/python3
# -*- coding: utf8 -*-

# Import module
import subprocess

out = subprocess.Popen("echo Hello", shell=True, stdout=subprocess.PIPE).stdout.read()
print(out)

b'Hello\n'