.\" 

.\" pkg-config manual page.

.\" (C) Red Hat, Inc. based on gnome-config man page (C) Miguel de Icaza (miguel@gnu.org)

.\"

.

.TH pkg-config 1

.SH NAME

pkg-config \- Return metainformation about installed libraries

.SH SYNOPSIS

.PP

.B pkg-config

[\-\-modversion] [\-\-version] [\-\-help] [\-\-print-errors]

[\-\-silence-errors] [\-\-errors-to-stdout] [\-\-debug]

[\-\-cflags] [\-\-libs] [\-\-libs-only-L]

[\-\-libs-only-l] [\-\-cflags-only-I]

[\-\-variable=VARIABLENAME]

[\-\-define-variable=VARIABLENAME=VARIABLEVALUE]

[\-\-print-variables]

[\-\-uninstalled]

[\-\-exists] [\-\-atleast-version=VERSION] [\-\-exact-version=VERSION]

[\-\-max-version=VERSION] [\-\-list\-all] [LIBRARIES...]

[\-\-print-provides] [\-\-print-requires] [\-\-print-requires-private] [LIBRARIES...]

.SH DESCRIPTION

The \fIpkg-config\fP 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:

.PP

.nf

program: program.c

	cc program.c $(pkg-config --cflags --libs gnomeui)

.fi

.PP

.I pkg-config

retrieves information about packages from special metadata

files. These files are named after the package, and has a

.I .pc

extension.  On most systems, \fIpkg-config\fP looks in

.I /usr/lib/pkgconfig, /usr/share/pkgconfig, /usr/local/lib/pkgconfig

and

.I /usr/local/share/pkgconfig

for these files.  It will additionally look in the colon-separated

(on Windows, semicolon-separated) list of directories specified by the

PKG_CONFIG_PATH environment variable.

.PP

The package name specified on the \fIpkg-config\fP command line is

defined to be the name of the metadata file, minus the \fI.pc\fP

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").

.PP

In addition to specifying a package name on the command line, the full

path to a given \fI.pc\fP file may be given instead. This allows a

user to directly query a particular \fI.pc\fP file.

.\"

.SH OPTIONS

The following options are supported:

.TP

.I "--modversion"

Requests that the version information of the libraries specified on

the command line be displayed.  If \fIpkg-config\fP 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 \fIpkg-config\fP

exits successfully. If one or more libraries is unknown,

.I pkg-config

exits with a nonzero code, and the contents of stdout are undefined.

.TP

.I "--version"

Displays the version of

.I pkg-config

and terminates.

.TP

.I "--help"

Displays a help message and terminates.

.TP

.I "--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 \fI.pc\fP file, then this option will cause errors explaining the

problem to be printed. With "predicate" options such as "--exists"

.I "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.

.TP

.I "--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 \fI.pc\fP file, then this option will keep errors explaining the

problem from being printed. With "predicate" options such as

"--exists" \fIpkg-config\fP 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.

.TP

.I "--errors-to-stdout"

If printing errors, print them to stdout rather than the default stderr

.TP

.I "--debug"

Print debugging information. This is slightly different than the

PKG_CONFIG_DEBUG_SPEW environment variable, which also enable

"--print-errors".

.PP

The following options are used to compile and link programs:

.TP

.I "--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. \fIpkg-config\fP exits with a nonzero code if it

can't find metadata for one or more of the packages on the command

line.

.TP

.I "--cflags-only-I"

This prints the -I part of "--cflags". That is, it defines the header

search path but doesn't specify anything else.

.TP 

.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.

.TP

.I "--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.

.TP

.I "--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.

.TP

.I "--variable=VARIABLENAME"

This returns the value of a variable defined in a package's \fI.pc\fP

file. Most packages define the variable "prefix", for example, so you 

can say:

.nf

  $ pkg-config --variable=prefix glib-2.0

  /usr/

.fi

.TP

.I "--define-variable=VARIABLENAME=VARIABLEVALUE"

This sets a global value for a variable, overriding the value in any

.I .pc

files. Most packages define the variable "prefix", for example, so you

can say:

.nf

  $ pkg-config --print-errors --define-variable=prefix=/foo \e

               --variable=prefix glib-2.0

  /foo

.fi

.TP

.I "--print-variables"

Returns a list of all variables defined in the package.

.TP

.I "--uninstalled"

Normally if you request the package "foo" and the package

"foo-uninstalled" exists, \fIpkg-config\fP will prefer the 

"-uninstalled" variant. This allows compilation/linking against

uninstalled packages. If you specify the "--uninstalled" option,

.I 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

.I 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.)

.TP

.I "--exists"

.TP

.I "--atleast-version=VERSION"

.TP

.I "--exact-version=VERSION"

.TP

.I "--max-version=VERSION"

These options test whether the package or list of packages on the

command line are known to \fIpkg-config\fP, and optionally whether the

version number of a package meets certain constraints.  If all packages

exist and meet the specified version constraints,

.I pkg-config

exits successfully. Otherwise it exits unsuccessfully. 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:

.nf

  $ pkg-config --exists 'glib-2.0 >= 1.3.4 libxml = 1.8.3'

.fi

Remember to use \-\-print-errors if you want error messages. When no

output options are supplied to \fIpkg-config\fP, \-\-exists is implied.

.TP

.I "--msvc-syntax"

This option is available only on Windows. It causes \fIpkg-config\fP

to output -l and -L flags in the form recognized by the Microsoft

Visual C++ command-line compiler, \fIcl\fP. Specifically, instead of

.I -Lx:/some/path

it prints \fI/libpath:x/some/path\fP, and instead of \fI-lfoo\fP it

prints \fIfoo.lib\fP. Note that the --libs output consists of flags

for the linker, and should be placed on the cl command line after a

/link switch.

.TP

.I "--dont-define-prefix"

This option is available only on Windows. It prevents \fIpkg-config\fP

from automatically trying to override the value of the variable

"prefix" in each .pc file.

.TP

.I "--prefix-variable=PREFIX"

Also this option is available only on Windows. It sets the name of the

variable that \fIpkg-config\fP automatically sets as described above.

.TP

.I "--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.

.TP

.I "--list-all"

List all modules found in the \fIpkg-config\fP path.

.TP

.I "--print-provides"

List all modules the given packages provides.

.TP

.I "--print-requires"

List all modules the given packages requires.

.TP

.I "--print-requires-private"

List all modules the given packages requires for static linking (see --static).

.\"

.SH ENVIRONMENT VARIABLES

.TP

.I "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

.I \%libdir/\fPpkgconfig:\fIdatadir\fP/pkgconfig where \fIlibdir\fP is

the libdir for \fIpkg-config\fP and \fIdatadir\fP is the datadir

for \fIpkg-config\fP when it was installed.

.TP

.I "PKG_CONFIG_DEBUG_SPEW"

If set, causes \fIpkg-config\fP to print all kinds of

debugging information and report all errors.

.TP

.I "PKG_CONFIG_TOP_BUILD_DIR"

A value to set for the magic variable \fIpc_top_builddir\fP

which may appear in \fI.pc\fP 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 \fIpkg-config\fP will be used.

This only matters when compiling/linking against a package that hasn't

yet been installed.

.TP

.I "PKG_CONFIG_DISABLE_UNINSTALLED"

Normally if you request the package "foo" and the package

"foo-uninstalled" exists, \fIpkg-config\fP will prefer the 

"-uninstalled" variant. This allows compilation/linking against

uninstalled packages.  If this environment variable is set, it

disables said behavior.

.TP

.I "PKG_CONFIG_ALLOW_SYSTEM_CFLAGS"

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

.TP

.I "PKG_CONFIG_ALLOW_SYSTEM_LIBS"

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

.TP

.I "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_CONFIG_SYSROOT_DIR

equal to /var/target (same rule apply to -L)

.TP

.I "PKG_CONFIG_LIBDIR"

Replaces the default \fIpkg-config\fP search directory, usually \fI/usr/lib/pkgconfig\fP

.\"

.SH QUERYING PKG-CONFIG'S DEFAULTS

.I pkg-config

can be used to query itself for the default search path, version number

and other information, for instance using:

.nf

  $ pkg-config --variable pc_path pkg-config

.fi

or

.nf

  $ pkg-config --modversion pkg-config

.fi

.SH 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 \fIprefix\fP variable is

overridden for that file accordingly.

If the value of a variable in a .pc file begins with the original,

non-overridden, value of the \fIprefix\fP variable, then the overridden

value of \fIprefix\fP is used instead.

.\"

.SH AUTOCONF MACROS

.TP

.I "PKG_CHECK_MODULES(VARIABLE-PREFIX, MODULES [,ACTION-IF-FOUND [,ACTION-IF-NOT-FOUND]])"

The macro PKG_CHECK_MODULES can be used in \fIconfigure.ac\fP to 

check whether modules exist. A typical usage would be:

.nf

 PKG_CHECK_MODULES([MYSTUFF], [gtk+-2.0 >= 1.3.5 libxml = 1.8.4])

.fi

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 \fIpkg-config\fP again.

.\"

.TP

.I "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.

.\"

.TP

.I "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.

.TP

.I "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.

.TP

.I "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 override through the

--with-noarch-pkgconfigdir parameter.

.TP

.I "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.

.SH METADATA FILE SYNTAX

To add a library to the set of packages \fIpkg-config\fP knows about,

simply install a \fI.pc\fP file. You should install this file to 

.I libdir\fP/pkgconfig.

.PP

Here is an example file:

.nf

# 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 

.fi

.PP

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.

.PP

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 \fIpkg-config\fP; variables do not, you can have any

variables that you wish (however, users may expect to retrieve the

usual directory name variables).

.PP

Note that variable references are written "${foo}"; you can escape

literal "${" as "$${".

.TP

.I "Name:"

This field should be a human-readable name for the package. Note that

it is not the name passed as an argument to \fIpkg-config\fP.

.TP

.I "Description:"

This should be a brief description of the package

.TP

.I "URL:"

An URL where people can get more information about and download the package

.TP

.I "Version:"

This should be the most-specific-possible package version string.

.TP

.I "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 \fIpkg-config\fP to perform extra sanity

checks. You may only mention the same package one time on the 

.I "Requires:"

line. If the version of a package is unspecified, any version will

be used with no checking.

.TP

.I Requires.private:

A list of packages required by this package. The difference from

.I Requires

is that the packages listed under

.I 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,

.I Requires.private

shall be used exclusively to specify the dependencies between the

libraries.

.TP

.I "Conflicts:"

This optional line allows \fIpkg-config\fP to perform additional

sanity checks, primarily to detect broken user installations.  The

syntax is the same as

.I "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 \fIpkg-config\fP will complain.

.TP

.I "Libs:"

This line should give the link flags specific to your package. 

Don't add any flags for required packages; \fIpkg-config\fP will 

add those automatically.

.TP

.I "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

.I Requires.private

in that it references libraries that do not have package files

installed.

.TP

.I "Cflags:"

This line should list the compile flags specific to your package. 

Don't add any flags for required packages; \fIpkg-config\fP will 

add those automatically.

.\"

.SH AUTHOR

.I 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.

.I gnome-config

was written by Miguel de Icaza, Raja Harinath and various hackers in

the GNOME team.  It was inspired by Owen Taylor's \fIgtk-config\fP

program.

.\"

.SH BUGS

\fIpkg-config\fP does not handle mixing of parameters with and without

= well.  Stick with one.

Bugs can be reported at http://bugs.freedesktop.org/ under the

.I pkg-config

component.