11.2.2 Linking against Libtool Libraries with Automake
Once you have set up your `Makefile.am' to create some Libtool
libraries. you will want to link an executable against them. You can do
this easily with
automake by using the program's qualified
bin_PROGRAMS = shell
shell_SOURCES = shell.c token.l
shell_LDADD = libshell.la
This will choose either the static or shared archive from the
`libshell.la' Libtool library depending on the target host and any
Libtool mode switches mentioned in the `Makefile.am', or passed to
configure. The chosen archive will be linked with any objects
generated from the listed sources to make an executable. Note that the
executable itself is a hidden file, and that in its place
libtool creates a wrapper script, See section 10.5 Executing Uninstalled Binaries.
As with the Libtool libraries, you can pass additional switches for the
libtool invocation in the qualified `LDFLAGS' macros to
control how the
shell executable is linked:
- Always choose static libraries where possible, and try to create a
completely statically linked executable.
- If you really want to use this flag on some targets, you can pass it in
an `LDFLAGS' macro. This is not overridden by the
configure `--enable-fast-install' switch. Executables
built with this flag will not need relinking to be executed from the
build tree on platforms which might have otherwise required it.
- You should use this option for any executables which are used only for
testing, or for generating other files and are consequently never
installed. By specifying this option, you are telling Libtool that the
executable it links will only ever be executed from where it is built in
the build tree. Libtool is usually able to considerably speed up the
link process for such executables.
- This switch is similar to `-all-static', except that it applies to
only the uninstalled Libtool libraries in the build tree. Where
possible the static archive from these libraries is used, but the
default linking mode is used for libraries which are already installed.
When debugging an executable, for example, it can be useful to
shell_LDFLAGS = -all-static
You can pass Libtool link options to all of the targets in a given
directory by using the unadorned `LDFLAGS' macro:
This is best reserved for directories which have targets of the same
type, all Libtool libraries or all executables for instance. The
technique still works in a mixed target type directory, and
libtool will ignore switches which don't make sense for
particular targets. It is less maintainable, and makes it harder to
understand what is going on if you do that though.