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CentOS 7.0 - man page for pkg-config (centos section 1)

pkg-config(1)									    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=VARIABLE-
       VALUE]	 [--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 extension.  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-sepa-
       rated  (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 simul-
       taneously, 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_CONFIG_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_CON-
	      FIG_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 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 -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_CONFIG_DISABLE_UNINSTALLED environment vari-
	      able 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-unin-
	      stalled" 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  con-
	      straints, pkg-config exits successfully. Otherwise it exits unsuccessfully.

	      Rather  than  using  the	version-test  options, you can simply give a version con-
	      straint 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.

       --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 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 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_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/target/usr/include/libfoo with a  PKG_CON-
	      FIG_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 overrid-
       den 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 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])

	      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_MOD-
	      ULES(), 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, 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  vari-
       able  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 version of the required package (using the opera-
	      tors =, <, >, >=, <=); specifying a version allows pkg-config to perform extra san-
	      ity  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 check-
	      ing.

       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  to  a  library,
	      Requires.private	shall be used exclusively to specify the dependencies between the
	      libraries.

       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
	      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 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 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-config component.

										    pkg-config(1)


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