sg

Search for a pattern in the current directory

$ sg -p '[pattern]'

$ sg -p '[console.log($ARG)]' -l javascript

$ sg -p '[old_code]' -r '[new_code]' -i

$ sg -p '[foo($A)]' -r '[bar($A)]' --update-all [path/to/files]

$ sg scan -c [sgconfig.yml]

$ sg scan -r [rule.yml]

$ sg -p '[pattern]' -C [3]

$ sg -p '[pattern]' --json

sg command [options] [paths...]

sg (ast-grep) is a fast CLI tool for structural code search, linting, and rewriting based on abstract syntax trees. Unlike text-based grep, it understands code syntax and matches patterns at the AST level, making searches more precise and language-aware.
Patterns use a familiar code-like syntax with metavariables ($VAR, $$$ARGS) to match arbitrary expressions. For example, console.log($MSG) matches any console.log call regardless of the argument. Multiple metavariables with the same name must match identical code.
The tool supports many languages including JavaScript, TypeScript, Python, Rust, Go, Java, C, C++, and more via tree-sitter parsers. Rules can be defined in YAML configuration files for consistent codebase scanning.

-p, --pattern pattern

AST pattern to match; use $VAR for wildcards

String to replace matched AST nodes

Specify the programming language

Extract specific AST node type from matches

Matching strictness (cst, smart, ast, relaxed, signature)

Start interactive editing session

Apply all rewrites without confirmation

Output as JSON (pretty, stream, compact)

Show lines after match

Show lines before match

Show context lines around match

Path to configuration file (default: sgconfig.yml)

run

Search code by pattern and optionally rewrite (default command)

Scan codebase using configuration files and rules

Run tests for ast-grep rules

Generate scaffolding files (project, rule, test, util)

Start Language Server Protocol for editor integration

Generate shell completion scripts

On Linux, sg may conflict with the system sg command (setgroups). Use the full name ast-grep or create an alias. Pattern syntax varies slightly between languages due to AST differences.

ast-grep was created by Herrington Darkholme and first released around 2022. Written in Rust with tree-sitter for parsing, it was designed as a modern alternative to text-based code search tools, enabling precise structural matching across multiple programming languages.

grep(1), rg(1), sed(1), semgrep(1)