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pkg-config


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 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.
              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_CON-
              FIG_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  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
       --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_CON-
              FIG_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 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
              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

       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 infor-
              mation 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  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.

       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_ALLOW_SYSTEM_CFLAGS
       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 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

       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 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.
              PKG_CHECK_MODULES will not print any error messages if you spec-
              ify  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 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.

       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 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.

              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)
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