pkg-config - Return metainformation about installed libraries
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=VARIABLEVALUE] [--print-variables] [--uninstalled] [--exists] [--atleast-version=VERSION] [--exact-version=VERSION] [--max-version=VERSION] [--validate] [--list-all] [--print-provides] [--print-requires] [--print-requires-private] [LIBRARIES...]
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
extension. 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 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").
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.
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 PKG_CONFIG_DEBUG_SPEW 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 PKG_CONFIG_DEBUG_SPEW 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 PKG_CONFIG_DEBUG_SPEW 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 command 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 (maintaining 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
PKG_CONFIG_DISABLE_UNINSTALLED 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
unsuccessfully. Only the first VERSION comparing option will be honored.
Subsequent options of this type will be ignored.
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. When no
output options are supplied to pkg-config
, --exists is
implied.
--validate
Checks the syntax of a package's .pc
file for validity. This
is the same as --exists except that dependencies are not verified. This
can be useful for package developers to test their .pc
file
prior to release:
$ pkg-config --validate ./my-package.pc
--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.
--define-prefix
--dont-define-prefix
These options control whether pkg-config
overrides the value
of the variable prefix
in each .pc file. With --define-prefix,
pkg-config
uses the installed location of the .pc file to
determine the prefix. --dont-define-prefix prevents this behavior. The
default is usually --define-prefix.
When this feature is enabled and a .pc file is found in a directory
named 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. This allows the
feature to work even when the variables have been expanded in the .pc
file.
--prefix-variable=PREFIX
Set the name of the variable that pkg-config
overrides
instead of prefix
when using the --define-prefix feature.
--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).
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:datadir/pkgconfig
where libdir
is the libdir for pkg-config and datadir is the datadir
for pkg-config when it 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_builddir
which
may appear in .pc files. If the environment 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 compiling/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 compilation/linking against
uninstalled packages. If this environment variable is set, it disables
said behavior.
PKG_CONFIG_SYSTEM_INCLUDE_PATH
A path variable containing system directories searched by the
compiler. This is normally /usr/include
.
CPATH
C_INCLUDE_PATH
CPLUS_INCLUDE_PATH
Additional paths to append to
PKG_CONFIG_SYSTEM_INCLUDE_PATH
. These correspond to environment
variables used by many compilers to affect the header search path. These
are ignored on Windows builds when --msvc-syntax is in use.
INCLUDE
Additional paths to append to PKG_CONFIG_SYSTEM_INCLUDE_PATH
on Windows builds when --msvc-syntax is in use. This corresponds to the
environment variable used by MSVC to add directories to the include file
search path.
PKG_CONFIG_ALLOW_SYSTEM_CFLAGS
Don't strip system paths out of Cflags. See
PKG_CONFIG_SYSTEM_INCLUDE_PATH
for the definition of system
paths.
PKG_CONFIG_SYSTEM_LIBRARY_PATH
A path variable containing system directories searched by the linker.
This is normally /usr/lib:/lib
but is dependent on the
pkg-config
build and can contain other directories such as
/usr/lib64
.
PKG_CONFIG_ALLOW_SYSTEM_LIBS
Don't strip system paths out of Libs. See
PKG_CONFIG_SYSTEM_LIBRARY_PATH
for the definition of system
paths.
PKG_CONFIG_SYSROOT_DIR
Modify -I and -L to use the directories located in target sysroot. 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/libfoo with a PKG_CONFIG_SYSROOT_DIR equal to /var/target (same rule apply to -L)
PKG_CONFIG_LIBDIR
Replaces the default pkg-config
search directory, usually
/usr/lib/pkgconfig
:/usr/share/pkgconfig
.
PKG_CONFIG_$PACKAGE_$VARIABLE
Overrides the variable VARIABLE in the package PACKAGE. The environment variable should have the package name and package variable upper cased with non-alphanumeric characters converted to underscores. For example, setting PKG_CONFIG_GLADEUI_2_0_CATALOGDIR will override the variable "catalogdir" in the "gladeui-2.0" package.
pkg-config
sets a few metadata variables that can be used in
.pc files or queried at runtime.
pc_path
The default search path used by pkg-config
when searching
for .pc files. This can be used in a query for the pkg-config
module itself itself:
$ pkg-config --variable pc_path pkg-config
pcfiledir
The installed location of the .pc file. This can be used to query the location of the .pc file for a particular module, but it can also be used to make .pc files relocatable. For instance:
prefix=${pcfiledir}/../..
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
includedir=${prefix}/include
pc_sysrootdir
The sysroot directory set by the user. When the sysroot directory has
not been set, this value is /
. See the
PKG_CONFIG_SYSROOT_DIR
environment variable for more
details.
pc_top_builddir
Location of the user's top build directory when calling
pkg-config.
This is useful to dynamically set paths in
uninstalled .pc files. See the PKG_CONFIG_TOP_BUILD_DIR
environment variable for more details.
The pkg-config
default search path is ignored on Windows.
Instead, the search path is constructed by using the installed directory
of pkg-config
and then appending lib\pkgconfig
and
share\pkgconfig
. This can be augmented or replaced using the
standard environment variables described above.
The macro PKG_CHECK_MODULES can be used in configure.ac 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.
Note that if there is a possibility the first call to PKG_CHECK_MODULES might not happen, you should be sure to include an explicit call to PKG_PROG_PKG_CONFIG in your configure.ac.
Also note that repeated usage of VARIABLE-PREFIX is not recommended.
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.
PKG_PREREQ(MIN-VERSION)
Checks that the version of the pkg-config autoconf macros in use is at least MIN-VERSION. This can be used to ensure a particular pkg-config macro will be available.
PKG_PROG_PKG_CONFIG([MIN-VERSION])
Defines the PKG_CONFIG variable to the best pkg-config available, useful if you need pkg-config but don't want to use PKG_CHECK_MODULES.
If the first call to PKG_PROG_PKG_CONFIG is conditional, then it will not work correctly in all cases. Since many of the other macros such as PKG_CHECK_MODULES require PKG_PROG_PKG_CONFIG to know which pkg-config program to run, PKG_PROG_PKG_CONFIG may be run for the first time from a conditional from one of these macros. Therefore, if any of the pkg-config macros will be used under a conditional, it's best to run PKG_PROG_PKG_CONFIG before any of the other macros are used.
Enables static linking through --static prior to calling PKG_CHECK_MODULES.
Check to see whether a particular set of modules exists. Similar to PKG_CHECK_MODULES(), but does not set variables or print errors.
Similar to PKG_CHECK_MODULES, make sure that the first instance of this or PKG_CHECK_MODULES is called, or make sure to call PKG_PROG_PKGCONFIG manually.
PKG_INSTALLDIR(DIRECTORY)
Substitutes the variable pkgconfigdir as the location where a module should install pkg-config .pc files. By default the directory is $libdir/pkgconfig, but the default can be changed by passing DIRECTORY. The user can override through the --with-pkgconfigdir parameter.
PKG_NOARCH_INSTALLDIR(DIRECTORY)
Substitutes the variable noarch_pkgconfigdir as the location where a module should install arch-independent pkg-config .pc files. By default the directory is $datadir/pkgconfig, but the default can be changed by passing DIRECTORY. The user can override through the --with-noarch-pkgconfigdir parameter.
Retrieves the value of the pkg-config variable CONFIG-VARIABLE from MODULE and stores it in VARIABLE. Note that repeated usage of VARIABLE is not recommended as the check will be skipped if the variable is already set.
To add a library to the set of packages pkg-config knows
about, simply install a .pc file. You should install this file
to libdir/pkgconfig.
Here is an example file:
# This is a comment
prefix=/home/hp/unst # this defines a variable
exec_prefix=${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
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${libdir}/glib/include
You would normally generate the file using configure, so that the prefix, etc. are set to the proper values. The GNU Autoconf manual recommends generating files like .pc files at build time rather than configure time, so when you build the .pc file is a matter of taste and preference.
Files have two kinds of line: keyword lines start with a keyword plus
a colon, and variable definitions start with an alphanumeric string plus
an equals sign. Keywords are defined in advance and have special meaning
to pkg-config; variables do not, you can have any
variables
that you wish (however, users may expect to retrieve the usual directory
name variables).
Note that variable references are written "${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
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 dynamically 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 dependencies between the libraries.
Conflicts:
This optional line allows pkg-config to perform additional
sanity 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 differs 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 package.
Don't add any flags for required packages; pkg-config will
add
those automatically.
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.
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-config
component.