Actual meaning of 'shell=True' in subprocess

Question

I am calling different processes with the subprocess module. However, I have a question.

In the following codes:

callProcess = subprocess.Popen(['ls', '-l'], shell=True)

and

callProcess = subprocess.Popen(['ls', '-l']) # without shell

Both work. After reading the docs, I came to know that shell=True means executing the code through the shell. So that means in absence, the process is directly started.

So what should I prefer for my case - I need to run a process and get its output. What benefit do I have from calling it from within the shell or outside of it.

Answer 1

You can understand the actual meaning of ‘shell=True’ in subprocess by below-mentioned example where things could go wrong with Shell=True is shown here:-

>>> from subprocess import call 

>>> filename = input("What file would you like to display?\n") 

>>> call("cat " + filename, shell=True)