Detect whether the terminal is legacy.

Checks if terminal is legacy (limited rendering, flicker-prone on rapid redraws, etc.). On Windows, returns True if CMD or PowerShell ISE not hosted in modern shell. On *nix systems, returns True if env.TERM is 'dumb' or 'unknown' (indicating a very basic terminal).

pip install is-legacy-terminal

is-legacy-terminal  # or islegacy
# e.g. => True

CLI options:

import is_legacy_terminal

if is_legacy_terminal():
    print('Is legacy terminal!')
else:
    print('Is modern terminal!')

Note: Most type checkers will falsely warn is_legacy_terminal is not a callable module because they are incapable of analyzing runtime behavior (where the module is replaced w/ a function for cleaner, direct access). You can safely suppress such warnings using # type: ignore.

Copyright © 2026 Adam Lui

🈶 is-unicode-supported - Detect whether the terminal supports advanced Unicode.

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