NAME
pkg-config - Return metainformation about installed libraries SYNOPSIS
pkg-config [modversion] [version] [help] [atleast-pkgconfig-
version=VERSION] [print-errors] [short-errors] [silence-errors]
[errors-to-stdout] [debug] [cflags] [libs] [libs-only-L]
[libs-only-l] [cflags-only-I] [libs-only-other] [cflags-only-
other] [variable=VARIABLENAME] [define-variable=VARIABLENAME=VARI‐
ABLEVALUE] [print-variables] [uninstalled] [exists] [atleast-
version=VERSION] [exact-version=VERSION] [max-version=VERSION]
[list-all] [LIBRARIES...] [print-provides] [print-requires]
[print-requires-private] [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 special metadata files. These files are named after the package, and has a .pc exten‐
sion. On most systems, pkg-config looks in /usr/lib/pkgconfig, /usr/share/pkgconfig, /usr/local/lib/pkgconfig and /usr/local/share/pkgconfig for these files. It will additionally look
in the colon-separated (on Windows, semicolon-separated) list of direc‐ tories specified by the PKGCONFIGPATH 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"). In addition to specifying a package name on the command line, the full path to a given .pc file may be given instead. This allows a user to directly query a particular .pc file. OPTIONS The following options are supported: modversion Requests that the version information of the libraries specified
on the command line be displayed. 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 undefined. version
Displays the version of pkg-config and terminates.
atleast-pkgconfig-version=VERSION
Requires at least the given version of pkg-config. 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 PKGCONFIGDEBUGSPEW environment variable overrides this option.
short-errors Print short error messages.
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 useful with options such as "cflags" or "modversion" that print errors by default. The PKGCON‐ FIGDEBUGSPEW environment variable overrides this option.
errors-to-stdout If printing errors, print them to stdout rather than the default stderr debug Print debugging information. This is slightly different than the PKGCONFIGDEBUGSPEW environment variable, which also enable
"print-errors". The following options are used to compile and link programs: 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 com‐ mand line.
cflags-only-I
This prints the -I part of "cflags". That is, it defines the header search path but doesn't specify anything else.
cflags-only-other
This prints parts of "cflags" not covered by "cflags-only- I". libs This option is identical to "cflags", only it prints the link flags. As with "cflags", duplicate flags are merged (maintain‐ ing proper ordering), 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.
libs-only-other
This prints the parts of "libs" not covered by "libs-only-L"
and "libs-only-l", such as "pthread". variable=VARIABLENAME This returns the value of a variable defined in a package's .pc file. Most packages define the variable "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 .pc files. Most packages define the variable "prefix", for example, so you can say:
$ pkg-config print-errors define-variable=prefix=/foo \
variable=prefix glib-2.0 /foo
print-variables Returns a list of all variables defined in the package. uninstalled
Normally if you request the package "foo" and the package "foo-
uninstalled" exists, pkg-config will prefer the "-uninstalled" variant. This allows compilation/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 PKGCON‐
FIGDISABLEUNINSTALLED environment variable keeps pkg-config
from implicitly 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 command 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-config, and optionally whether the version number of a package meets certain constraints. If all packages exist and meet the specified version constraints,
pkg-config exits successfully. Otherwise it exits unsuccess‐ fully.
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 Micro‐
soft 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 prevents pkg-config from automatically trying to override 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 automatically sets as described above. static Output libraries suitable for static linking. That means including any private libraries in the output. This relies on proper tagging in the .pc files, else a too large number of libraries will ordinarily be output.
list-all
List all modules found in the pkg-config path.
print-provides List all modules the given packages provides.
print-requires List all modules the given packages requires.
print-requires-private List all modules the given packages requires for static linking (see static). ENVIRONMENT VARIABLES PKGCONFIGPATH
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:datadir/pkgconfig where libdir is the libdir
for pkg-config and datadir is the datadir for pkg-config when it was installed. PKGCONFIGDEBUGSPEW
If set, causes pkg-config to print all kinds of debugging infor‐ mation and report all errors. PKGCONFIGTOPBUILDDIR A value to set for the magic variable pctopbuilddir which may appear in .pc files. If the environment variable is not set, the
default value '$(topbuilddir)' will be used. This variable should refer to the top builddir of the Makefile where the com‐
pile/link flags reported by pkg-config will be used. This only matters when compiling/linking against a package that hasn't yet been installed. PKGCONFIGDISABLEUNINSTALLED
Normally if you request the package "foo" and the package "foo-
uninstalled" exists, pkg-config will prefer the "-uninstalled" variant. This allows compilation/linking against uninstalled packages. If this environment variable is set, it disables said behavior. PKGCONFIGALLOWSYSTEMCFLAGS
Don't strip -I/usr/include out of cflags. PKGCONFIGALLOWSYSTEMLIBS
Don't strip -L/usr/lib out of libs PKGCONFIGSYSROOTDIR
Modify -I and -L to use the directories located in target sys‐
root. this option is useful when cross-compiling packages that
use pkg-config to determine CFLAGS and LDFLAGS. -I and -L are modified to point to the new system root. this means that a
-I/usr/include/libfoo will become -I/var/target/usr/include/lib‐ foo with a PKGCONFIGSYSROOTDIR equal to /var/target (same
rule apply to -L) PKGCONFIGLIBDIR
Replaces the default pkg-config search directory, usually /usr/lib/pkgconfig
QUERYING PKG-CONFIG'S DEFAULTS
pkg-config can be used to query itself for the default search path, version number and other information, for instance using:
$ pkg-config variable pcpath pkg-config or
$ pkg-config modversion pkg-config WINDOWS SPECIALITIES If a .pc file is found in a directory that matches the usual conven‐ tions (i.e., ends with \lib\pkgconfig or \share\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.
If the value of a variable in a .pc file begins with the original, non- overridden, value of the prefix variable, then the overridden value of prefix is used instead. AUTOCONF MACROS
PKGCHECKMODULES(VARIABLE-PREFIX, MODULES [,ACTION-IF-FOUND [,ACTION-
IF-NOT-FOUND]]) The macro PKGCHECKMODULES can be used in configure.ac to check whether modules exist. A typical usage would be:
PKGCHECKMODULES([MYSTUFF], [gtk+-2.0 >= 1.3.5 libxml = 1.8.4]) This would result in MYSTUFFLIBS and MYSTUFFCFLAGS substitu‐ tion 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. PKGCHECKMODULES will not print any error messages if you spec‐
ify your own ACTION-IF-NOT-FOUND. However, it will set the variable MYSTUFFPKGERRORS, which you can use to display what went wrong. Note that if there is a possibility the first call to PKGCHECKMODULES might not happen, you should be sure to include an explicit call to PKGPROGPKGCONFIG in your config‐ ure.ac.
Also note that repeated usage of VARIABLE-PREFIX is not recom‐ mended. After the first successful usage, subsequent calls with
the same VARIABLE-PREFIX will simply use the LIBS and CFLAGS
variables set from the previous usage without calling pkg-config again.
PKGPROGPKGCONFIG([MIN-VERSION])
Defines the PKGCONFIG variable to the best pkg-config avail‐
able, useful if you need pkg-config but don't want to use PKGCHECKMODULES.
PKGCHECKEXISTS(MODULES, [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND]) Check to see whether a particular set of modules exists. Simi‐ lar to PKGCHECKMODULES(), but does not set variables or print errors. Similar to PKGCHECKMODULES, make sure that the first instance of this or PKGCHECKMODULES is called, or make sure to call PKGCHECKEXISTS manually. 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
execprefix=${prefix} # defining another variable in terms of the first
libdir=${execprefix}/lib
includedir=${prefix}/include
Name: GObject # human-readable name
Description: Object/type system for GLib # human-readable description Version: 1.3.1 URL: http://www.gtk.org
Requires: glib-2.0 = 1.3.1 Conflicts: foobar <= 4.5
Libs: -L${libdir} -lgobject-1.3
Libs.private: -lm
Cflags: -I${includedir}/glib-2.0 -I${libdir}/glib/include You would normally generate the file using configure, so that the pre‐ fix, etc. are set to the proper values. The GNU Autoconf manual recom‐ mends generating files like .pc files at build time rather than config‐ ure time, so when you build the .pc file is a matter of taste and pref‐ erence. 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 mean‐
ing 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 "${foo}"; you can escape lit‐
eral "${" 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 URL: An URL where people can get more information about and download 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 operators =, <,
>, >=, <=); 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. Requires.private: A list of packages required by this package. The difference from Requires is that the packages listed under Requires.private are not taken into account when a flag list is computed for dynami‐ cally linked executable (i.e., when static was not specified). In the situation where each .pc file corresponds to a library, Requires.private shall be used exclusively to specify the depen‐ dencies between the libraries. Conflicts:
This optional line allows pkg-config to perform additional san‐ ity checks, primarily to detect broken 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 mentioned package. If a user tries to use your
package 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. Libs.private: This line should list any private libraries in use. Private libraries are libraries which are not exposed through your library, but are needed in the case of static linking. This dif‐ fers from Requires.private in that it references libraries that do not have package files installed. Cflags: This line should list the compile flags specific to your pack‐
age. Don't add any flags for required packages; pkg-config will add those automatically. AUTHOR
pkg-config was written by James Henstridge, rewritten by Martijn van Beers, and rewritten again by Havoc Pennington. 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
pkg-config does not handle mixing of parameters with and without = well. Stick with one.
Bugs can be reported at http://bugs.freedesktop.org/ under the pkg-con‐ fig component.
pkg-config(1)