How to redirect output with subprocess in Python?

Question

What I do in the command line:

cat file1 file2 file3 > myfile 

What I want to do with python:

import subprocess, shlex my_cmd = 'cat file1 file2 file3 > myfile' args = shlex.split(my_cmd) subprocess.call(args) # spits the output in the window i call my python program 

Answer 1

In Python 3.5+ to redirect the output, just pass an open file handle for the stdout argument to subprocess.run:

# Use a list of args instead of a string input_files = ['file1', 'file2', 'file3'] my_cmd = ['cat'] + input_files with open('myfile', "w") as outfile:     subprocess.run(my_cmd, stdout=outfile) 

As others have pointed out, the use of an external command like cat for this purpose is completely extraneous.