Full text searching in Info mode with Apropos
Most Emacs hackers quickly memorize the myriad of help commands available to them in Emacs; among them, the humble
M-x apropos command, a full text regexp search command that searches all known Lisp symbols (macros, functions, variables – you name it) and returns a list of matches. I should point out that — as the two are often confused — it has a closely-related sibling
M-x apropos-command, bound to
C-h a, that will only search interactive commands*.
What most people are not aware of is a little-known command named
info-apropos, a full text search for Emacs’s documentation browser,
C-h i.) Not limited to just your Emacs documentation, the
info-apropos command will also search other info documentation present on your system, such as the GNU CoreUtils manuals. What sets it apart from existing info commands like
C-s (isearch) is that it will give you a full list of all matches and tell you what node it was found under. Very useful.
* – Of course, there are many more domain-specific apropos commands – use
C-h a to find them