Emacs offers a dizzying number of commands to perform bulk operations on multiple files or buffers. These commands are quite capable and can make trivial the execution of workflows that would be heroic in other editors. Unfortunately these commands are also difficult to discover as a number of them are not featured in easily accessible menus.

This post calls attention to bulk commands related to search and replace in Emacs and how their discoverability can be improved using the Casual and Anju UI packages.

Regular Expressions

Before moving forward, let’s talk about how Emacs handles regular expression syntax in search and/or replace commands. Whenever using an Emacs command involving a regular expression (regexp), you will need to understand what kind of regexp syntax is expected. There are largely two to know:

• Emacs
• grep (implementation dependent)

Commands using grep-style regexps do so because they invoke the local install of the grep utility. The grep regex syntax is implementation dependent. If you use GNU grep, you can read its syntax here, which share some character classes with Emacs.

The Casual RE-Builder package is a great way to work with Emacs regexps as it provides a command to escape the regexp properly for interactive input. re-builder alone only provides a regexp that can be used in Elisp code.

Bulk Search & Replace Commands

The table below shows the different search and/or replace workflows and their associated commands.

Choice of command depends on the quantity and specificity of files or buffers to work on. Both Dired and IBuffer marking allow for specific selection of files or buffers respectively.

Many of the commands in the table above are discoverable via menu using the Casual and Anju packages. Hierarchical menu categorization aids in the discovery and recognition of these commands, making them more usable.

Refactoring Guidance

The replace commands can do catastrophic damage if not used with caution. Treat them like power tools.

Some guidance before using replace commands:

1. Have a backup plan in case you need to recover anything.

2. Use re-builder to help figure out the right regexp.

3. Know the scope of what you want to change (directory, files, buffers).

4. Some commands will only modify the buffer of an affected file. Check if modified buffers are saved. You can use IBuffer to identify and save such buffers. It is left as an exercise to the reader to determine which commands exhibit this behavior.

Closing Thoughts

The inventory of commands above are from what I know of Emacs, which is guaranteed to not be comprehensive. If there are others missing from this list, please let me know at kickingvegas@gmail.com.

While many of these commands have been in Emacs for years (decades even), they were not usable to me until I built a UI for them. I think motivated readers using Casual and Anju for bulk search and/or replace tasks will find a similar sentiment.

Amended 2026-04-30: Added vc-git-grep, eglot-rename, xref-find-references-and-replace, and xref-query-replace-in-results. Thanks to Henry Leach and Gene Pasquet for their input!

emacs