This section describes miscellaneous search-related customizations not described elsewhere.
The default search mode for the incremental search is specified by
the variable search-default-mode. It can be
t, or a function. If it is
nil, the default mode is to
do literal searches without character folding, but with case folding
and lax-whitespace matches as determined by case-fold-search
and search-whitespace-regexp, respectively (see Lax Search). If the value is t, incremental search defaults to
regexp searches. The default value specifies a function that only
performs case folding and lax-whitespace matching.
The current match of an on-going incremental search is highlighted
isearch face. This highlighting can be disabled by
setting the variable search-highlight to
The other matches for the search string that are visible on display
are highlighted using the
lazy-highlight face. Setting the
variable isearch-lazy-highlight to
nil disables this
highlighting. Here are some other variables that customize the lazy
Time in seconds to wait before highlighting visible matches.
Time in seconds between highlighting successive matches.
The maximum number of matches to highlight before checking for input. A large number can take some time to highlight, so if you want to continue searching and type C-s or C-r during that time, Emacs will not respond until it finishes highlighting all those matches. Thus, smaller values make Emacs more responsive.
Normally, entering RET within incremental search when the
search string is empty launches a nonincremental search. (Actually,
it lets you edit the search string, and the next RET does the
search.) However, if you customize the variable
nil, typing RET
will always exit the incremental search, even if the search string is
By default, incremental search and query-replace commands match
invisible text, but hide any such matches as soon as the current match
moves off the invisible text. If you customize the variable
nil, any invisible text
where matches were found stays on display until the search or the
replace command exits.
Searching incrementally on slow terminals, such as displays connected to remote machines over slow connection, could be annoying due to the need to redraw large portions of the display as the search proceeds. Emacs provides a special display mode for slow terminals, whereby search pops up a separate small window and displays the text surrounding the match in that window. Small windows display faster, so the annoying effect of slow speed is alleviated. The variable search-slow-speed determines the baud rate threshold below which Emacs will use this display mode. The variable search-slow-window-lines controls the number of lines in the window Emacs pops up for displaying the search results; the default is 1 line. Normally, this window will pop up at the bottom of the window that displays the buffer where you start searching, bit if the value of search-slow-window-lines is negative, that means to put the window at the top and give it the number of lines that is the absolute value of that value.