Using an Environment Variable

You can also use the environment variable LD_LIBRARY_PATH, which takes a colon-separated list of directories, to add to the link-editor's library search path. In its most general form, LD_LIBRARY_PATH takes two directory lists separated by a semicolon. The first list is searched before the list(s) supplied on the command-line, and the second list is searched after. There is also an LD_LIBRARY_PATH_64 environment variable that overrides any active LD_LIBRARY_PATH setting when processing 64-bit objects.

Here is the combined effect of setting LD_LIBRARY_PATH and calling the link-editor with several -L occurrences:

$ LD_LIBRARY_PATH=dir1:dir2;dir3
$ export LD_LIBRARY_PATH
$ cc -o prog main.c -Lpath1 ... -Lpath2 ... -Lpathn -lfoo

The effective search path will be dir1:dir2:path1:path2... pathn:dir3:/usr/ccs/lib:/usr/lib.

If no semicolon is specified as part of the LD_LIBRARY_PATH definition, the specified directory list is interpreted after any -L options. For example:

$ LD_LIBRARY_PATH=dir1:dir2
$ export LD_LIBRARY_PATH
$ cc -o prog main.c -Lpath1 ... -Lpath2 ... -Lpathn -lfoo
 

Here the effective search path will be path1:path2... pathn:dir1:dir2:/usr/ccs/lib:/usr/lib.

This environment variable can also be used to augment the search path of the runtime linker (see "Directories Searched by the Runtime Linker" for more details). To prevent this environment variable from influencing the link-editor, use the -i option.