Linting

badness lint parses each file and reports diagnostics, rendered with source snippets pointing at the offending range. It exits non-zero when there is at least one diagnostic, which makes it usable as a CI gate.

badness lint paper.tex
cat paper.tex | badness lint   # stdin

Parse diagnostics

Alongside the rules, the linter surfaces parse diagnostics: places where the parser recovered from malformed input. Because the parser is error-tolerant, a single problem never aborts the parse—badness anchors recovery on clean LaTeX boundaries (\end{…}, \begin, a blank line, }, $, &, \\) and keeps going, so one file can report several independent diagnostics in one run. Parse diagnostics carry the rule id parse and are never silenced by select/ignore.

Rules

Beyond parse recovery, badness ships a growing set of built-in rules (deprecated-command, dollar-display-math, undefined-ref, and more). Each has a stable id used in diagnostics, config, and suppression comments. See the Linter Rules reference for the full catalogue, or print a single rule’s description and examples from the terminal:

badness lint --explain deprecated-command

Every rule is on by default. Narrow the active set through the [lint] table or the matching CLI flags:

[lint]
select = ["deprecated-command", "dollar-display-math"]  # allowlist
ignore = ["missing-nonbreaking-space"]                  # turn off

Suppress a rule at one site with a comment directive:

% badness-ignore deprecated-command: legacy code
{\bf here}

Some rules ship an auto-fix. badness lint --fix applies the meaning-preserving (Safe) ones; --unsafe-fixes also applies fixes that may change output, such as missing-nonbreaking-space (inserting a tie changes line breaking), abbreviation-spacing (inserting \ or \@ changes sentence spacing), or space-before-command (deleting a space before \footnote changes spacing).