ast-grep

ast-grep (ast-grep or sg) searches code by AST structure, not text. Patterns must be valid parseable code with $VAR meta-variables for wildcards.

Core Commands

# Search with pattern
ast-grep run -l ts --pattern 'console.log($X)' src/

# Search in directory (auto-detects language)
ast-grep run --pattern '$FUNC()' agent/extensions/

Pattern Syntax

• $VAR — matches single AST node (uppercase only: $MOD, $_, $_123)
• $$$VAR — matches zero or more nodes (function args, statements)
• $_VAR — non-capturing (same name can match different content)
• Patterns must be valid code: import { $X } from "$Y" works, from $X fails