15.1.5 Special Input for Incremental Search

In addition to characters described in the previous subsections, some of the other characters you type during incremental search have special effects. They are described here.

To toggle lax space matching (see lax space matching), type M-s SPC.

To toggle case sensitivity of the search, type M-c or M-s c. See case folding. If the search string includes upper-case letters, the search is case-sensitive by default.

To toggle whether or not the search will consider similar and equivalent characters as a match, type M-s '. See character folding. If the search string includes accented characters, that disables character folding during that search.

To toggle whether or not invisible text is searched, type M-s i (isearch-toggle-invisible). See Outline Search.

To toggle between non-regexp and regexp incremental search, type M-r or M-s r (isearch-toggle-regexp). See Regexp Search.

To toggle symbol mode, type M-s _. See Symbol Search.

To search for a newline character, type C-j as part of the search string.

To search for non-ASCII characters, use one of the following methods:

• Type C-q, followed by a non-graphic character or a sequence of octal digits. This adds a character to the search string, similar to inserting into a buffer using C-q (see Inserting Text). For example, C-q C-s during incremental search adds the ‘control-S’ character to the search string.
• Type C-x 8 RET, followed by a Unicode name or code-point in hex. This adds the specified character into the search string, similar to the usual insert-char command (see Inserting Text).
• Use an input method (see Input Methods). If an input method is enabled in the current buffer when you start the search, the same method will be active in the minibuffer when you type the search string. While typing the search string, you can toggle the input method with C-\ (isearch-toggle-input-method). You can also turn on a non-default input method with C-^ (isearch-toggle-specified-input-method), which prompts for the name of the input method. When an input method is active during incremental search, the search prompt includes the input method mnemonic, like this:

  I-search [im]:
  

  where im is the mnemonic of the active input method. Any input method you enable during incremental search remains enabled in the current buffer afterwards.

Typing M-s o in incremental search invokes isearch-occur, which runs occur with the current search string. See occur.

Typing M-% in incremental search invokes query-replace or query-replace-regexp (depending on search mode) with the current search string used as the string to replace. A negative prefix argument means to replace backward. See Query Replace.

Typing M-TAB in incremental search invokes isearch-complete, which attempts to complete the search string using the search ring (the previous search strings you used) as a list of completion alternatives. See Completion. In many operating systems, the M-TAB key sequence is captured by the window manager; you then need to rebind isearch-complete to another key sequence if you want to use it (see Rebinding).

You can exit the search while leaving the matches for the last search string highlighted on display. To this end, type M-s h r (isearch-highlight-regexp), which will run highlight-regexp (see Highlight Interactively) passing it the regexp derived from the last search string and prompting you for the face to use for highlighting. To remove the highlighting, type M-s h u (unhighlight-regexp).

When incremental search is active, you can type C-h C-h (isearch-help-map) to access interactive help options, including a list of special key bindings. These key bindings are part of the keymap isearch-mode-map (see Keymaps).