This is another note to myself. For some reason I have a hard time remembering the handful of commands that do things to the lines in a buffer that match a regular expression. The table below are the ones that I know about but have a hard time remembering. If you have any similar commands that you find useful, leave a comment.
| Command | Alias | Action |
|---|---|---|
| keep-lines | delete-non-matching-lines | Delete lines not matching regexp |
| flush-lines | delete-matching-lines | Delete lines matching regexp |
| how-many | count-matches | Count lines matching regexp |
| occur | list-matching-lines | Show lines matching regexp in another buffer |
| highlight-lines-matching-regexp | hi-lock-line-face-buffer | Highlight lines matching regexp |
Update Phil reminds me of highlight-lines-matching-regexp, which I meant to include but forgot. (See what I mean?) He also mentions multi-occur (just like occur but it acts on multiple buffers) and multi-occur-in-matching-buffers (like multi-occur but you specify the buffers with a regexp), which he says he finds particularly useful.