.\" $OpenBSD: library-specs.7,v 1.6 2006/08/03 11:56:25 jmc Exp $
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.\" Copyright (c) 2001 Marc Espie
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.Dd April 9, 2001
.Dt LIBRARY-SPECS 7
.Os
.Sh NAME
.Nm library-specs
.Nd shared library name specifications
.Sh DESCRIPTION
Each
.Ev LIB_DEPENDS
item in the port tree conforms to
.Sq lib_specs:[pkgspec]:directory[,-subpackage][,flavor ...][:target] ,
where
.Sq lib_specs
is a comma-separated list of
.Sq lib_spec
of the form:
.Sq libname[.=major[.minor]]
or
.Sq libname[.>=major[.minor]] .
.Pp
All libraries that a port needs must be mentioned in that list, either
directly or indirectly through recursive dependencies (except, of course,
for system libraries).
.Pp
The package system will embed correct dependency checks in the built
package, according to the normal shared library semantics: any library with
the same major number, and a greater or equal minor number will do.
.Pp
Therefore, porters must strive to respect correct shared library semantics
in their own ports: by bumping the minor number each time the interface is
augmented, and by bumping the major number each time the interface changes.
Note that adding functions to a library is an interface augmentation.
Removing functions is an interface change.
.Pp
The major.minor components of the library specification are used only as a
build-time check.
For
.Sq libname.>=major[.minor] ,
any library which is more recent than the given major.minor version will
do.
If a specific major number is needed, use the form
.Sq libname.=major[.minor] .
If the minor component is left empty, any minor will do.
If both components are left empty, any version will do.
.Pp
The
.Sq pkgspec
part is always checked, both at build-time, and at
.Xr pkg_add 1
time.
If
.Sq pkgspec
is left empty, any package will do: in effect, the pkgspec used is
.Sq stem-* .
.Pp
If a given architecture does not support shared libraries, all
.Ev LIB_DEPENDS
will be turned into simple
.Ev BUILD_DEPENDS
checks.
Failure to mention
.Ev RUN_DEPENDS
if the port needs anything beyond libraries from the dependent port will
lead to strange errors.
.Sh SEE ALSO
.Xr pkg_add 1 ,
.Xr bsd.port.mk 5 ,
.Xr packages 7 ,
.Xr packages-specs 7 ,
.Xr ports 7
.Sh HISTORY
Full support for library specifications first appeared in
.Ox 3.1 .
The format of specifications changed slightly to include
.Sq >=
before
.Ox 4.0 .