When working with Python, there may be times when you need to execute a shell command or script. One common requirement is to run a non-interactive shell command from Python. In this article, we will explore three different ways to achieve this using Python.

Option 1: Using the subprocess module

The subprocess module in Python provides a way to spawn new processes, connect to their input/output/error pipes, and obtain their return codes. We can use this module to execute a shell command non-interactively.

import subprocess

command = "ls -l"
result = subprocess.run(command, shell=True, capture_output=True, text=True)
print(result.stdout)

In this example, we use the subprocess.run() function to execute the shell command “ls -l”. The shell=True argument tells the function to use the shell as the program to execute. The capture_output=True argument captures the command’s output, and the text=True argument returns the output as a string instead of bytes. Finally, we print the output using result.stdout.

Option 2: Using the os module

The os module in Python provides a way to interact with the operating system. We can use the os.system() function to execute a shell command non-interactively.

import os

command = "ls -l"
os.system(command)

In this example, we use the os.system() function to execute the shell command “ls -l”. The function returns the exit status of the command, but it does not capture the command’s output. If you need to capture the output, you can redirect it to a file and then read the file using Python.

Option 3: Using the subprocess module with Popen

Another way to execute a shell command non-interactively is by using the subprocess module with the Popen class. This class provides more flexibility and control over the execution of the command.

import subprocess

command = "ls -l"
process = subprocess.Popen(command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
output, error = process.communicate()
print(output)

In this example, we use the subprocess.Popen() function to execute the shell command “ls -l”. The stdout=subprocess.PIPE argument captures the command’s output, and the stderr=subprocess.PIPE argument captures any error messages. The communicate() method returns a tuple containing the output and error messages. Finally, we print the output using output.

After exploring these three options, the best approach depends on your specific requirements. If you only need to execute a simple shell command and capture its output, Option 1 using the subprocess module is a good choice. If you don’t need to capture the output or want a simpler solution, Option 2 using the os module can be sufficient. However, if you require more control over the execution or need to capture both the output and error messages, Option 3 using the subprocess module with Popen is the most suitable.