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subprocess.run() for safer command execution

subprocess.run() is the safest default for running external commands from Python. It is clearer and less error-prone than older process APIs or shell-string hacks.

Why it is useful​

import subprocess

result = subprocess.run(
    ["python3", "--version"],
    check=True,
    capture_output=True,
    text=True,
)

print(result.stdout.strip())

This pattern gives you:

  • explicit arguments
  • output capture
  • clear failure handling with check=True

Prefer argument lists over shell strings​

Passing a list avoids many quoting problems and is usually safer than building one shell command string by hand.

When to be careful​

Only use shell=True when you truly need shell behavior and understand the tradeoffs.

Rules of thumb​

  • Prefer subprocess.run() for external commands.
  • Pass arguments as a list.
  • Use check=True when command failure should raise an error.