pkg-config


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=VARIABLE-
       VALUE] [--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 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, 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_CON-
       FIG_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
              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


       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.

       --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.


       --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



       --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 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.


ENVIRONMENT VARIABLES
       PKG_CONFIG_PATH
              A colon-separated  (on  Windows,  semicolon-separated)  list  of
              directories to search for .pc files.  The default directory will
              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 out of libs


       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  conven-
       tions  (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\pkgconfig\PKG_CONFIG_PATH      and
       HKEY_LOCAL_MACHINE\Software\pkgconfig\PKG_CONFIG_PATH  can  be  used to
       specify directories 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 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

              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_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


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 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 "$${".
              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.

       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.


       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.
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