Although the library search mechanism, in dynamic mode, searches a given directory for a shared object, then an archive library, finer control of the type of search required can be achieved using the -B option.
By specifying the -Bdynamic and -Bstatic options on the command-line, as many times as required, the library search can be toggled between shared objects or archives respectively. For example, to link an application with the archive libfoo.a and the shared object libbar.so, issue the following command:
$ cc -o prog main.o file1.c -Bstatic -lfoo -Bdynamic -lbar
The -Bstatic and -Bdynamic keywords are not exactly symmetrical. When you specify -Bstatic, the link-editor does not accept shared objects as input until the next occurrence of -Bdynamic. However, when you specify -Bdynamic, the link-editor first looks for shared objects and then archives in any given directory.
In the previous example it is more precise to say that the link-editor first searches for libfoo.a, and then for libbar.so, and if that fails, for libbar.a. Finally, it will search for libc.so, and if that fails, libc.a.