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pkg-config(1)                                                    pkg-config(1)



NAME
       pkg-config - Return metainformation about installed libraries

SYNOPSIS
       pkg-config  [--modversion]  [--help]  [--print-errors]  [--silence-errors]  [--cflags] [--libs] [--libs-only-L]
       [--libs-only-l]  [--cflags-only-I]   [--variable=VARIABLENAME]   [--define-variable=VARIABLENAME=VARIABLEVALUE]
       [--uninstalled]   [--exists]   [--atleast-version=VERSION]   [--exact-version=VERSION]  [--max-version=VERSION]
       [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, with the extension .pc. By default, pkg-config looks in the directory prefix/lib/pkgconfig  for  these
       files; it will also 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").


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.

       --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 envi-
              ronment variable overrides this option.


       --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


       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.

       --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.


       --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


       --uninstalled
              Normally if you request the package "foo" and the package "foo-uninstalled" exists, pkg-config will pre-
              fer 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 contraints.  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  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 automat-
              ically 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.


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/pkgcon-
              fig:datadir/pkgconfig  where libdir is the libdir where pkg-config and datadir is the datadir where pkg-
              config 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 pre-
              fer 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 out of libs


       PKG_CONFIG_SYSROOT_DIR
              Modify  -I  and -L to use the directories located in target sysroot.  this option is usefull when cross-
              compiling package that use pkg-config to determine CFLAGS anf 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.


WINDOWS SPECIALITIES
       If a .pc file is found in a directory that matches the usual conventions (i.e., ends with \lib\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.

       In addition to the PKG_CONFIG_PATH environment variable, the Registry  keys  HKEY_CURRENT_USER\Software\pkgcon-
       fig\PKG_CONFIG_PATH  and  HKEY_LOCAL_MACHINE\Software\pkgconfig\PKG_CONFIG_PATH can be used to specify directo-
       ries to search for .pc files. Each (string) value in these keys is treated as a directory where to look for .pc
       files.


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

              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.

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

              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_CHECK_EXISTS 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
       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, of course, so that the prefix, etc. are set to the proper
       values.


       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 pack-
              ages  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.

       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 pack-
              age.  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 pack-
              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.


       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 writ-
       ten 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.



                                                                 pkg-config(1)