11.8 Other Search-and-Loop Commands

Here are some other commands that find matches for a regular expression. They all ignore case in matching, if the pattern contains no upper-case letters and case-fold-search is non-nil. Aside from occur, all operate on the text from point to the end of the buffer, or on the active region in Transient Mark mode.

M-x occur <RET> regexp <RET>

Display a list showing each line in the buffer that contains a match for regexp. To limit the search to part of the buffer, narrow to that part (see Narrowing). A numeric argument n specifies that n lines of context are to be displayed before and after each matching line.

The buffer `*Occur*' containing the output serves as a menu for finding the occurrences in their original context. Click Mouse-2 on an occurrence listed in `*Occur*', or position point there and type <RET>; this switches to the buffer that was searched and moves point to the original of the chosen occurrence.

M-x list-matching-lines

Synonym for M-x occur.

M-x how-many <RET> regexp <RET>

Print the number of matches for regexp that exist in the buffer after point. In Transient Mark mode, if the region is active, the command operates on the region instead.

M-x flush-lines <RET> regexp <RET>

Delete each line that contains a match for regexp, operating on the text after point. In Transient Mark mode, if the region is active, the command operates on the region instead.

M-x keep-lines <RET> regexp <RET>

Delete each line that does not contain a match for regexp, operating on the text after point. In Transient Mark mode, if the region is active, the command operates on the region instead.

You can also search multiple files under control of a tags table (see Tags Search) or through Dired A command (see Operating on Files), or ask the grep program to do it (see Grep Searching).