pkg-config(1)



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=VARI-
       ABLEVALUE] [--print-variables] [--uninstalled]  [--exists]  [--atleast-
       version=VERSION]    [--exact-version=VERSION]   [--max-version=VERSION]
       [--validate]   [--list-all]    [--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.

       --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_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
              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_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. 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  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.

       --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 direc-
              tory 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  origi-
              nal,  non-overridden,  value  of  the  prefix variable, then the
              overridden value of prefix is used instead. This allows the fea-
              ture  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).

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
              Don't strip -I/usr/include out of cflags.

       PKG_CONFIG_ALLOW_SYSTEM_LIBS
              Don't strip -L/usr/lib or -L/lib out of libs.

       PKG_CONFIG_SYSROOT_DIR
              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 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 DERIVED VARIABLES
       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 direc-
              tory has not been set, this value is /.  See the PKG_CONFIG_SYS-
              ROOT_DIR environment variable for more details.

       pc_top_builddir
              Location of the user's top build directory when calling pkg-con-
              fig.  This is useful to dynamically set paths in uninstalled .pc
              files. See the PKG_CONFIG_TOP_BUILD_DIR environment variable for
              more details.

WINDOWS SPECIALITIES
       The pkg-config default search path is ignored on Windows. Instead,  the
       search path is constructed by using the installed directory of pkg-con-
       fig and then appending lib\pkgconfig and share\pkgconfig.  This can  be
       augmented   or   replaced  using  the  standard  environment  variables
       described above.

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_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 avail-
              able, useful if you  need  pkg-config  but  don't  want  to  use
              PKG_CHECK_MODULES.

       PKG_CHECK_MODULES_STATIC(VARIABLE-PREFIX,   MODULES   [,ACTION-IF-FOUND
       [,ACTION-IF-NOT-FOUND]])
              Enables  static  linking  through  --static  prior  to   calling
              PKG_CHECK_MODULES.

       PKG_CHECK_EXISTS(MODULES, [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])

              Check  to see whether a particular set of modules exists.  Simi-
              lar 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_CHECK_EXISTS 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  over-
              ride through the --with-noarch-pkgconfigdir parameter.

       PKG_CHECK_VAR(VARIABLE,   MODULE,  CONFIG-VARIABLE,  [ACTION-IF-FOUND],
       [ACTION-IF-NOT-FOUND])

              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.

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.

       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)

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