reference > Rule syntax

languages

See also

--show-supported-languages, --lang, pattern-regex, generic_engine

A list of languages. The rule runs on the files of each of these languages, and its patterns are parsed as code of the first language of the list. Every rule must have languages, with at least one language; a single language is still written as a list, [python].

Each language has a name and some aliases: python can also be written py, javascript js, typescript ts. --show-supported-languages lists them. An unknown name makes the rule invalid, and the scan exits with status 8.

Since the patterns are parsed in the first language only, a rule with several languages is suited to languages that share a syntax, such as JavaScript and TypeScript, or C and C++.

Two values are not programming languages:

• generic runs the rule on every file, regardless of its extension. Its patterns are matched as text in which brackets and quotes nest; see generic_engine.
• regex, also spelled none, runs the rule on every file with pattern-regex and the other regular-expression keys only.

## Examples

### Two languages with a shared syntax

rules:  - id: inner-html    pattern: $EL.innerHTML = $VALUE    message: assignment to innerHTML    languages: [javascript, typescript]    severity: WARNING

el.innerHTML = comment;

el.innerHTML = comment;

$ opengrep scan -q --config rule.yaml --files-with-matches .
app.js
app.ts

### An unknown language

rules:  - id: find-eval    pattern: eval(...)    message: found eval    languages: [pyton]    severity: WARNING

eval(1)

$ opengrep scan --config rule.yaml app.py > /dev/null 2>&1; echo "exit status: $?"
exit status: 8