diff options
Diffstat (limited to 'make.texinfo')
| -rw-r--r-- | make.texinfo | 28 |
1 files changed, 25 insertions, 3 deletions
diff --git a/make.texinfo b/make.texinfo index e7b3bbf..246707c 100644 --- a/make.texinfo +++ b/make.texinfo @@ -1971,16 +1971,19 @@ directory search with no extra effort. @cindex @code{VPATH}, and link libraries @cindex search path for dependencies (@code{VPATH}), and link libraries @cindex @code{-l} (library search) +@cindex link libraries, patterns matching +@cindex @code{.LIBPATTERNS}, and link libraries +@vindex .LIBPATTERNS Directory search applies in a special way to libraries used with the linker. This special feature comes into play when you write a dependency whose name is of the form @samp{-l@var{name}}. (You can tell something strange is going on here because the dependency is normally the name of a -file, and the @emph{file name} of the library looks like +file, and the @emph{file name} of a library generally looks like @file{lib@var{name}.a}, not like @samp{-l@var{name}}.)@refill When a dependency's name has the form @samp{-l@var{name}}, @code{make} -handles it specially by searching for the file @file{lib@var{name}.a} in +handles it specially by searching for the file @file{lib@var{name}.so} in the current directory, in directories specified by matching @code{vpath} search paths and the @code{VPATH} search path, and then in the directories @file{/lib}, @file{/usr/lib}, and @file{@var{prefix}/lib} @@ -1988,7 +1991,11 @@ directories @file{/lib}, @file{/usr/lib}, and @file{@var{prefix}/lib} @code{make} behave as if @var{prefix} is defined to be the root of the DJGPP installation tree). -For example, +If that file is not found, then the file @file{lib@var{name}.a} is +searched for, in the same directories as above. + +For example, if there is a @file{/usr/lib/libcurses.a} library on your +system (and no @file{/usr/lib/libcurses.so} file), then @example @group @@ -2002,6 +2009,21 @@ would cause the command @samp{cc foo.c /usr/lib/libcurses.a -o foo} to be executed when @file{foo} is older than @file{foo.c} or than @file{/usr/lib/libcurses.a}.@refill +Although the default set of files to be searched for is +@file{lib@var{name}.so} and @file{lib@var{name}.a}, this is customizable +via the @code{.LIBPATTERNS} variable. Each word in the value of this +variable is a pattern string. When a dependency like +@samp{-l@var{name}} is seen, @code{make} will replace the percent in +each pattern in the list with @var{name} and perform the above directory +searches using that library filename. If no library is found, the next +word in the list will be used. + +The default value for @code{.LIBPATTERNS} is ``@samp{lib%.so lib%.a}'', +which provides the default behavior described above. + +You can turn off link library expansion completely by setting this +variable to an empty value. + @node Phony Targets, Force Targets, Directory Search, Rules @section Phony Targets @cindex phony targets |