An archive file that is used as a library usually contains a special member
named __.SYMDEF that contains a directory of the external symbol
names defined by all the other members. After you update any other
members, you need to update __.SYMDEF so that it will summarize the
other members properly. This is done by running the ranlib program:
ranlib archivefile
Normally you would put this command in the rule for the archive file, and make all the members of the archive file prerequisites of that rule. For example,
libfoo.a: libfoo.a(x.o) libfoo.a(y.o) ...
ranlib libfoo.a
The effect of this is to update archive members x.o, y.o,
etc., and then update the symbol directory member __.SYMDEF by
running ranlib. The rules for updating the members are not shown
here; most likely you can omit them and use the implicit rule which copies
files into the archive, as described in the preceding section.
This is not necessary when using the GNU ar program, which
updates the __.SYMDEF member automatically.