6 Searching an Info File

GNU Info allows you to search for a sequence of characters throughout an entire Info file, search through the indices of an Info file, or find areas within an Info file which discuss a particular topic.

s (search)

/

Read a string in the echo area and search for it, either as a regular expression (by default) or a literal string. If the string includes upper-case characters, the Info file is searched case-sensitively; otherwise Info ignores the letter case. With a numeric argument of N, search for Nth occurrence of the string. Negative arguments search backwards.

Normally, the search pattern should not be shorter than some predefined limit. By default, this limit is set to 1 character. See min-search-length, for more information on this.

M-x search-backward

?, vi-like operation

Read a string in the echo area and search backward through the Info file for that string. If the string includes upper-case characters, the Info file is searched case-sensitively; otherwise Info ignores the letter case. With a numeric argument of N, search for Nth occurrence of the string. Negative arguments search forward.

If you do not have a convenient key sequence bound to this command, an alternative is to first perform a forward search, and then use the search-previous command, described below.

R (toggle-regexp)

Toggle between using regular expressions and literal strings for searching. Info uses so-called ‘extended’ regular expression syntax (see Regular Expressions in GNU Grep).

S (search-case-sensitively

Read a string in the echo area and search for it case-sensitively, even if the string includes only lower-case letters. With a numeric argument of N, search for Nth occurrence of the string. Negative arguments search backwards.

C-x n (search-next)

}

n, vi-like operation

Search for the same string used in the last search command, in the same direction, and with the same case-sensitivity option. With a numeric argument of n, search for nth next occurrence.

By default, the search starts at the position immediately following the cursor. However, if the variable search-skip-screen (see search-skip-screen) is set, it starts at the beginning of the next page, thereby skipping all visibly displayed lines (but not any further lines in the current node).

C-x N (search-previous)

{

N, vi-like operation

Search for the same string used in the last search command, and with the same case-sensitivity option, but in the reverse direction. With a numeric argument of n, search for the nth previous occurrence.

By default, the search starts at the position immediately preceding the cursor, but skips visible lines if the variable search-skip-screen is set, as with } (see preceding item).

C-s (isearch-forward)

Interactively search forward through the Info file for a string as you type it. If the string includes upper-case characters, the search is case-sensitive; otherwise Info ignores the letter case.

C-r (isearch-backward)

Interactively search backward through the Info file for a string as you type it. If the string includes upper-case characters, the search is case-sensitive; otherwise Info ignores the letter case.

i (index-search)

Look up a string in the indices for this Info file, and select a node to which the found index entry points. If you press RET without giving a string, Info takes you to an index node in the file.

I (virtual-index)

Look up a string in the indices for this Info file, and show all the matches in a new virtual node, synthesized on the fly.

, (next-index-match)

Move to the node containing the next matching index item from the last ‘i’ command.

M-x index-apropos

Grovel the indices of all the known Info files on your system for a string, and build a menu of the possible matches.

The most basic searching command is ‘s’ or ‘/’ (search). The ‘s’ command prompts you for a string in the echo area, and then searches the remainder of the Info file for an occurrence of that string. If the string is found, the node containing it is selected, and the cursor is left positioned at the start of the found string. Subsequent ‘s’ commands show you the default search string within ‘[’ and ‘]’; pressing RET instead of typing a new string will use the default search string.

Using the ‘}’ or ‘{’ commands (or the ‘n’ or ‘N’ commands under ‘--vi-keys’; see --vi-keys), is a faster way of searching for the same string.

If the highlight-searches variable is set, matches from search commands will be highlighted. See highlight-searches. Use the M-x clear-search command to clear any search highlights.

Incremental searching is similar to basic searching, but the string is looked up while you are typing it, instead of waiting until the entire search string has been specified.

Both incremental and non-incremental search by default ignore the case of letters when comparing the Info file text with the search string. However, an uppercase letter in the search string makes the search case-sensitive. You can force a case-sensitive non-incremental search, even for a string that includes only lower-case letters, by using the ‘S’ command (search-case-sensitively). The ‘n’ and ‘N’ commands operate case-sensitively if the last search command was ‘S’.

The most efficient means of finding something quickly in a manual is the ‘i’ command (index-search). This command prompts for a string, and then looks for that string in all the indices of the current Info manual. If it finds a matching index entry, it displays the node to which that entry refers and prints the full text of the entry in the echo area. You can press ‘,’ (next-index-match) to find more matches. A good Info manual has all of its important concepts indexed, so the ‘i’ command lets you use a manual as a reference.

If you don’t know what manual documents something, try the M-x index-apropos command. It prompts for a string and then looks up that string in all the indices of all the Info documents installed on your system. It can also be invoked from the command line; see --apropos.