Linux命令——pkg-config

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=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

              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.

       --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

       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

       --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 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 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

              always be searched after searching the path; the default is lib-

              dir/pkgconfig: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 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 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

              default  action,  specify an ACTION-IF-NOT-FOUND. PKG_CHECK_MOD-

              ULES 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.

              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.

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 "$${".

       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.

       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.