The -L switch is used to list library directories on the command line. (See -I in -I for one example.) The value listed with this -L switch is appended to the values specified in your site-file with confLIBDIRS (confLIBDIRS), and to whatever values might be preset as defaults in your devtools/OS file. The final assembled value is made a part of your configuration file, and is also made the value of the LIBDIRS directive in your Makefile.

Multiple -L switches can be used to specify a series of library directories to search. For example:

% ./Build -L/usr/local/lib -L/usr/tools/lib

In general, library directories should be listed with the confLIBDIRS build macro (confLIBDIRS) in your m4 build file, instead of on the command line.