man pkg config Command

Man page for apt-get pkg config Command

Man Page for pkg config in Linux

Ubuntu Man Command : man pkg config

Man Pkg Config  Command

This tutorial shows the man page for man pkg config in linux.

Open terminal with 'su' access and type the command as shown below:
man pkg config

Result of the Command Execution shown below:

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=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.

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 config
ure.ac

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.

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:


Related Topics

Apt Get Commands