Bug report

Bug description:

subprocess.Popen doesn't properly escape < or > for windows batch files

example.bat

echo %*

example.py

import subprocess
from pathlib import Path

batch_file = Path().cwd() / 'example.bat'
subprocess.Popen([batch_file, 'arg1', 'arg2<99'])

Error

The system cannot find the file specified

Adding a space causes it to be correctly escaped:

subprocess.Popen([batch_file, 'arg1', 'arg2 <99'])

CPython versions tested on:

3.13

Operating systems tested on:

Windows

Linked PRs

• gh-133545: Also quote arguments containing &<>^| on Windows #134544