FileNotFoundError in subprocess: Command Not Found

Why This Happens

subprocess.run() looks for the executable on the system PATH. If not installed or misspelled, it raises FileNotFoundError.

The Problem

import subprocess
result = subprocess.run(['my-script', '--flag'])

The Fix

import subprocess, shutil
if shutil.which('my-script'):
    result = subprocess.run(['my-script', '--flag'])
else:
    print('my-script is not installed')

Step-by-Step Fix

1. 1

   Verify command exists

   Use shutil.which('command') to check.

2. 2

   Use full path

   Specify the complete path to the executable.

3. 3

   Check shell features

   Use shell=True for pipes/redirects, but avoid with untrusted input.