pkg-config(1)pkg-config(1)NAMEpkg-config - Return metainformation about installed
libraries
SYNOPSISpkg-config [--modversion] [--help] [--print-errors]
[--silence-errors] [--cflags] [--libs] [--libs-only-L]
[--libs-only-l] [--cflags-only-I] [--variable=VARIABLE-
NAME] [--define-variable=VARIABLENAME=VARIABLEVALUE]
[--uninstalled] [--exists] [--atleast-version=VERSION]
[--exact-version=VERSION] [--max-version=VERSION]
[LIBRARIES...]
DESCRIPTION
The pkg-config program is used to retrieve information
about installed libraries in the system. It is typically
used to compile and link against one or more libraries.
Here is a typical usage scenario in a Makefile:
program: program.c
cc program.c `pkg-config --cflags --libs gnomeui`
pkg-config retrieves information about packages from spe-
cial metadata files. These files are named after the pack-
age, with the extension .pc. By default, pkg-config looks
in the directory prefix/lib/pkgconfig for these files; it
will also look in the colon-separated (on Windows, semi-
colon-separated) list of directories specified by the
PKG_CONFIG_PATH environment variable.
The package name specified on the pkg-config command line
is defined to be the name of the metadata file, minus the
.pc extension. If a library can install multiple versions
simultaneously, it must give each version its own name
(for example, GTK 1.2 might have the package name "gtk+"
while GTK 2.0 has "gtk+-2.0").
OPTIONS
The following options are supported:
--modversion
Requests that the version information of the
libraries specified on the command line be dis-
played. If pkg-config can find all the libraries
on the command line, each library's version string
is printed to stdout, one version per line. In this
case pkg-config exits successfully. If one or more
libraries is unknown, pkg-config exits with a
nonzero code, and the contents of stdout are unde-
fined.
--help Displays a help message and terminates.
--print-errors
If one or more of the modules on the command line,
or their dependencies, are not found, or if an
error occurs in parsing a .pc file, then this
option will cause errors explaining the problem to
be printed. With "predicate" options such as
"--exists" pkg-config runs silently by default,
because it's usually used in scripts that want to
control what's output. This option can be used
alone (to just print errors encountered locating
modules on the command line) or with other options.
The PKG_CONFIG_DEBUG_SPEW environment variable
overrides this option.
--silence-errors
If one or more of the modules on the command line,
or their dependencies, are not found, or if an
error occurs in parsing a a .pc file, then this
option will keep errors explaining the problem from
being printed. With "predicate" options such as
"--exists" pkg-config runs silently by default,
because it's usually used in scripts that want to
control what's output. So this option is only use-
ful with options such as "--cflags" or "--modver-
sion" that print errors by default. The PKG_CON-
FIG_DEBUG_SPEW environment variable overrides this
option.
--errors-to-stdout
If printing errors, print them to stdout rather
than the default stderr
The following options are used to compile and link pro-
grams:
--cflags
This prints pre-processor and compile flags
required to compile the packages on the command
line, including flags for all their dependencies.
Flags are "compressed" so that each identical flag
appears only once. pkg-config exits with a nonzero
code if it can't find metadata for one or more of
the packages on the command line.
--libs This option is identical to "--cflags", only it
prints the link flags. As with "--cflags", dupli-
cate flags are merged (maintaining proper order-
ing), and flags for dependencies are included in
the output.
--libs-only-L
This prints the -L/-R part of "--libs". That is, it
defines the library search path but doesn't specify
which libraries to link with.
--libs-only-l
This prints the -l part of "--libs" for the
libraries specified on the command line. Note that
the union of "--libs-only-l" and "--libs-only-L"
may be smaller than "--libs", due to flags such as
-rdynamic.
--variable=VARIABLENAME
This returns the value of a variable defined in a
package's .pc file. Most packages define the vari-
able "prefix", for example, so you can say:
$ pkg-config --variable=prefix glib-2.0
/usr/
--define-variable=VARIABLENAME=VARIABLEVALUE
This sets a global value for a variable, overriding
the value in any example, so you can say:
$ pkg-config--print-errors --define-variable=prefix=/foo --variable=prefix glib-2.0
/foo
--uninstalled
Normally if you request the package "foo" and the
package "foo-uninstalled" exists, pkg-config will
prefer the "-uninstalled" variant. This allows com-
pilation/linking against uninstalled packages. If
you specify the "--uninstalled" option, pkg-config
will return successfully if any "-uninstalled"
packages are being used, and return failure (false)
otherwise. (The "PKG_CONFIG_DISABLE_UNINSTALLED"
environment variable keeps pkg-config from implic-
itly choosing "-uninstalled" packages, so if that
variable is set, they will only have been used if
you pass a name like "foo-uninstalled" on the com-
mand line explicitly.)
--exists
--atleast-version=VERSION
--exact-version=VERSION
--max-version=VERSION
These options test whether the package or list of
packages on the command line are known to pkg-con-
fig, and optionally whether the version number of a
package meets certain contraints. If all packages
exist and meet the specified version constraints,
pkg-config exits successfully. Otherwise it exits
unsuccessfully.
Rather than using the version-test options, you can
simply give a version constraint after each package
name, for example:
$ pkg-config--exists 'glib-2.0 >= 1.3.4 libxml = 1.8.3'
Remember to use --print-errors if you want error
messages.
--msvc-syntax
This option is available only on Windows. It causes
pkg-config to output -l and -L flags in the form
recognized by the Microsoft Visual C++ command-line
compiler, cl. Specifically, instead of
-Lx:/some/path it prints /libpath:x/some/path, and
instead of -lfoo it prints foo.lib. Note that the
--libs output consists of flags for the linker, and
should be placed on the cl command line after a
/link switch.
--dont-define-prefix
This option is available only on Windows. It pre-
vents pkg-config from automatically trying to over-
ride the value of the variable "prefix" in each .pc
file.
--prefix-variable=PREFIX
Also this option is available only on Windows. It
sets the name of the variable that pkg-config auto-
matically sets as described above.
ENVIRONMENT VARIABLES
PKG_CONFIG_PATH
A colon-separated (on Windows, semicolon-separated)
list of directories to search for .pc files. The
default directory will always be searched after
searching the path; the default is libdir/pkgconfig
where libdir is the libdir where pkg-config was
installed.
PKG_CONFIG_DEBUG_SPEW
If set, causes pkg-config to print all kinds of
debugging information and report all errors.
PKG_CONFIG_TOP_BUILD_DIR
A value to set for the magic variable pc_top_build-
dir which may appear in .pc files. If the environ-
ment variable is not set, the default value
'$(top_builddir)' will be used. This variable
should refer to the top builddir of the Makefile
where the compile/link flags reported by pkg-config
will be used. This only matters when compil-
ing/linking against a package that hasn't yet been
installed.
PKG_CONFIG_DISABLE_UNINSTALLED
Normally if you request the package "foo" and the
package "foo-uninstalled" exists, pkg-config will
prefer the "-uninstalled" variant. This allows com-
pilation/linking against uninstalled packages. If
this environment variable is set, it disables said
behavior.
PKG_CONFIG_ALLOW_SYSTEM_CFLAGS
Don't strip -I/usr/include out of cflags.
PKG_CONFIG_ALLOW_SYSTEM_LIBS
Don't strip -L/usr/lib out of libs
PKG_CONFIG_LIBDIR
Replaces the default pkg-config search directory.
WINDOWS SPECIALITIES
If a .pc file is found in a directory that matches the
usual conventions (i.e., ends with \lib\pkgconfig), the
prefix for that package is assumed to be the grandparent
of the directory where the file was found, and the prefix
variable is overridden for that file accordingly.
In addition to the PKG_CONFIG_PATH environment variable,
the Registry keys HKEY_CURRENT_USER\Software\pkgcon-
fig\PKG_CONFIG_PATH and
HKEY_LOCAL_MACHINE\Software\pkgconfig\PKG_CONFIG_PATH can
be used to specify directories to search for .pc files.
Each (string) value in these keys is treated as a direc-
tory where to look for .pc files.
AUTOCONF MACROS
PKG_CHECK_MODULES(VARIABLEBASE,MODULELIST[,ACTION-IF-
FOUND,[ACTION-IF-NOT-FOUND]])
The macro PKG_CHECK_MODULES can be used in config-
ure.in to check whether modules exist. A typical
usage would be:
PKG_CHECK_MODULES(MYSTUFF, gtk+-2.0 >= 1.3.5 libxml = 1.8.4)
This would result in MYSTUFF_LIBS and
MYSTUFF_CFLAGS substitution variables, set to the
libs and cflags for the given module list. If a
module is missing or has the wrong version, by
default configure will abort with a message. To
replace the default action, specify an ACTION-IF-
NOT-FOUND. PKG_CHECK_MODULES will not print any
error messages if you specify your own ACTION-IF-
NOT-FOUND. However, it will set the variable
MYSTUFF_PKG_ERRORS, which you can use to display
what went wrong.
If you want to use MYSTUFF_LIBS and MYSTUFF_CFLAGS
as Makefile.am variables (i.e. $(MYSTUFF_LIBS))
then you have to add AC_SUBST(MYSTUFF_LIBS) to your
configure.in so automake can find the variable. You
don't need to do this if you use the @MYSTUFF_LIBS@
syntax in your Makefile.am instead of
$(MYSTUFF_LIBS).
METADATA FILE SYNTAX
To add a library to the set of packages pkg-config knows
about, simply install a .pc file. You should install this
file to libdir/pkgconfig.
Here is an example file:
# This is a comment
prefix=/home/hp/unst # this defines a variable
exec_prefix=${prefix} # defining another variable in terms of the first
libdir=${exec_prefix}/lib
includedir=${prefix}/include
Name: GObject # human-readable name
Description: Object/type system for GLib # human-readable description
Version: 1.3.1
Requires: glib-2.0 = 1.3.1
Conflicts: foobar <= 4.5
Libs: -L${libdir} -lgobject-1.3
Cflags: -I${includedir}/glib-2.0 -I${libdir}/glib/include
You would normally generate the file using configure, of
course, so that the prefix, etc. are set to the proper
values.
Files have two kinds of line: keyword lines start with a
keyword plus a colon, and variable definitions start with
an alphanumeric string plus an equals sign. Keywords are
defined in advance and have special meaning to pkg-config;
variables do not, you can have any variables that you wish
(however, users may expect to retrieve the usual directory
name variables).
Note that variable references are written "${foo}"; you
can escape literal "${" as "$${".
Name: This field should be a human-readable name for the
package. Note that it is not the name passed as an
argument to pkg-config.
Description:
This should be a brief description of the package
Version:
This should be the most-specific-possible package
version string.
Requires:
This is a comma-separated list of packages that are
required by your package. Flags from dependent
packages will be merged in to the flags reported
for your package. Optionally, you can specify the
version of the required package (using the opera-
tors =, <, >, >=, <=); specifying a version allows
pkg-config to perform extra sanity checks. You may
only mention the same package one time on the
Requires: line. If the version of a package is
unspecified, any version will be used with no
checking.
Conflicts:
This optional line allows pkg-config to perform
additional sanity checks, primarily to detect bro-
ken user installations. The syntax is the same as
Requires: except that you can list the same package
more than once here, for example "foobar = 1.2.3,
foobar = 1.2.5, foobar >= 1.3", if you have reason
to do so. If a version isn't specified, then your
package conflicts with all versions of the men-
tioned package. If a user tries to use your pack-
age and a conflicting package at the same time,
then pkg-config will complain.
Libs: This line should give the link flags specific to
your package. Don't add any flags for required
packages; pkg-config will add those automatically.
Cflags:
This line should list the compile flags specific to
your package. Don't add any flags for required
packages; pkg-config will add those automatically.
AUTHORpkg-config was written by James Henstridge, rewritten by
Martijn van Beers, and rewritten again by Havoc Penning-
ton. Tim Janik, Owen Taylor, and Raja Harinath submitted
suggestions and some code. gnome-config was written by
Miguel de Icaza, Raja Harinath and various hackers in the
GNOME team. It was inspired by Owen Taylor's gtk-config
program.
BUGS
Hah!
pkg-con1ig(1)
