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pkg-config(1)                                  General Commands Manual                                  pkg-config(1)



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=VARIABLEVALUE] [--print-variables] [--uninstalled] [--exists]  [--atleast-ver‐
       sion=VERSION]  [--exact-version=VERSION]  [--max-version=VERSION]  [--list-all]  [LIBRARIES...]  [--print-pro‐
       vides] [--print-requires] [--print-requires-private] [LIBRARIES...]

DESCRIPTION
       The pkg-config program is used to retrieve information about installed libraries in the system.  It  is  typi‐
       cally 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/pkgcon‐
       fig,  /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.

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 PKG_CONFIG_DEBUG_SPEW
              environment variable overrides this option.

              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  pack‐
              ages 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 -rdy‐
              namic.

       --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.


       --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.

              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 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  auto‐
              matically sets as described above.

       --static
              Output  libraries  suitable for static linking.  That means including any private libraries in the out‐
              put.  This relies on proper tagging in the .pc files, else a too large number of libraries  will  ordi‐
              narily 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
       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.

              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_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/tar‐
              get/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

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 pc_path pkg-config
       or
         $ pkg-config --modversion pkg-config

WINDOWS SPECIALITIES
       If  a  .pc  file is found in a directory that matches the usual conventions (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 vari‐
       able, then the overridden value of prefix is used instead.

AUTOCONF MACROS
       PKG_CHECK_MODULES(VARIABLE-PREFIX, MODULES [,ACTION-IF-FOUND [,ACTION-IF-NOT-FOUND]])

              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_PROG_PKG_CONFIG([MIN-VERSION])


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
       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 ver‐
              sion 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
              ages; 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.

AUTHOR
       pkg-config  was written by James Henstridge, rewritten by Martijn van Beers, and rewritten again by Havoc Pen‐
       nington. 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 Tay‐
       lor'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-config component.



                                                                                                        pkg-config(1)