File: libtool.info,  Node: Release numbers,  Prev: Updating version info,  Up: Versioning

7.4 Managing release information
================================

Often, people want to encode the name of the package release into the
shared library so that it is obvious to the user what package their
programs are linked against.  This convention is used especially on
GNU/Linux:

     trick$ ls /usr/lib/libbfd*
     /usr/lib/libbfd.a           /usr/lib/libbfd.so.2.7.0.2
     /usr/lib/libbfd.so
     trick$

   On ‘trick’, ‘/usr/lib/libbfd.so’ is a symbolic link to
‘libbfd.so.2.7.0.2’, which was distributed as a part of
‘binutils-2.7.0.2’.

   Unfortunately, this convention conflicts directly with libtool's idea
of library interface versions, because the library interface rarely
changes at the same time that the release number does, and the library
suffix is never the same across all platforms.

   So, to accommodate both views, you can use the ‘-release’ flag to set
release information for libraries for which you do not want to use
‘-version-info’.  For the ‘libbfd’ example, the next release that uses
libtool should be built with ‘-release 2.9.0’, which will produce the
following files on GNU/Linux:

     trick$ ls /usr/lib/libbfd*
     /usr/lib/libbfd-2.9.0.so     /usr/lib/libbfd.a
     /usr/lib/libbfd.so
     trick$

   In this case, ‘/usr/lib/libbfd.so’ is a symbolic link to
‘libbfd-2.9.0.so’.  This makes it obvious that the user is dealing with
‘binutils-2.9.0’, without compromising libtool's idea of interface
versions.

   Note that this option causes a modification of the library name, so
do not use it unless you want to break binary compatibility with any
past library releases.  In general, you should only use ‘-release’ for
package-internal libraries or for ones whose interfaces change very
frequently.