ruff noqa: Suppress Specific Violations
A # noqa comment on a line tells Ruff to ignore violations there, optionally limited to specific rule codes.
noqa is the escape hatch for a single justified violation. Codes make it precise; Ruff itself can flag noqa comments that are no longer needed.
What it does
Appending # noqa to a line suppresses all violations on it; # noqa: E501,F401 suppresses only those codes. The RUF100 rule flags noqa comments that suppress nothing (unused-noqa), and ruff check --add-noqa inserts noqa comments for existing violations.
Common usage
import os # noqa: F401
x = 1 # noqa
very_long_line = "..." # noqa: E501
# auto-insert noqa for every current violation
ruff check --add-noqa .Behavior and config
| Item | What it does |
|---|---|
| # noqa | Suppress every violation on the line |
| # noqa: <codes> | Suppress only the listed rule codes |
| RUF100 | Rule that flags unused (stale) noqa comments |
| --add-noqa | Insert noqa comments for current violations |
| # ruff: noqa | File-level directive to disable noqa enforcement |
In CI
Always write code-specific noqa (# noqa: F401), not a bare # noqa, so a real bug on the same line is not hidden. Enable RUF100 so CI fails when a noqa becomes stale, which keeps suppressions honest as rules and code change.
Common errors in CI
"RUF100 Unused noqa directive" means a suppression no longer matches any violation, often after a fix; remove the comment. A bare # noqa silently hiding a new violation is a common review miss. --add-noqa is a migration aid, not a CI step; running it in a pipeline edits files and leaves a dirty tree.