fastmod

Replace string in files

$ fastmod "[old_string]" "[new_string]"

$ fastmod -m "[pattern]" "[replacement]"

$ fastmod "[old]" "[new]" [directory]

$ fastmod --extensions "[py,js]" "[old]" "[new]"

$ fastmod --accept-all "[old]" "[new]"

$ fastmod --print-only "[old]" "[new]"

fastmod [options] pattern replacement [paths...]

fastmod performs fast, interactive codemod operations across files. It searches for patterns and offers interactive confirmation for replacements, making bulk code changes safer.
The tool combines the speed of ripgrep for searching with interactive review of changes. It's designed for large-scale refactoring in codebases.

-m, --multiline

Enable multiline regex matching.

Case insensitive matching.

Filter by file extensions.

Accept all replacements.

Show matches without changing.

Search directory.

Include/exclude files.

Search hidden files.

Treat pattern as literal.

Regex syntax differs from some tools. Interactive mode requires terminal. Large replacements may need review. Backup recommended before bulk changes.

fastmod was developed at Facebook (Meta) as a tool for large-scale code modifications. It addresses the need for interactive, safe refactoring across massive codebases. Released as open source, it uses Rust for performance.

sed(1), ripgrep(1), codemod(1), comby(1)