pkgconf/README.md

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# pkgconf
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pkgconf provides compiler and linker configuration for development frameworks.
## general summary
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pkgconf is a program which helps to configure compiler and linker flags for
development frameworks.
It is similar to pkg-config, but was written from scratch in the summer of 2011
to replace pkg-config, which for a while needed itself to build itself (they have
since included a 'stripped down copy of glib 2.0') Since then we have worked on
improving pkg-config for embedded use.
If you're wondering what pkg-config is useful for, you might find the tutorial/guide
docs for [legacy pkg-config][pcdocs] useful.
[pcdocs]: http://people.freedesktop.org/~dbn/pkg-config-guide.html
## usage
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Implementations of pkg-config, such as pkgconf, are typically used with the
PKG_CHECK_MODULES autoconf macro. As far as we know, pkgconf is
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compatible with all known variations of this macro. pkgconf detects at
runtime whether or not it was started as 'pkg-config', and if so, attempts
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to set program options such that its behaviour is similar.
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In terms of the autoconf macro, it is possible to specify the PKG_CONFIG
environment variable, so that you can test pkgconf without overwriting your
pkg-config binary. Some other build systems may also respect the PKG_CONFIG
environment variable.
To set the enviornment variable on the bourne shell and clones (i.e. bash), you
can run:
$ export PKG_CONFIG=/usr/bin/pkgconf
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## technical design (why pkgconf is better for distros)
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pkgconf builds an acyclic directed dependency graph. This allows for the user
to more conservatively link their binaries -- which may be helpful in some
environments, such as when prelink(1) is being used. As a result of building
a directed dependency graph designed for the specific problem domain provided
by the user, more accurate dependencies can be determined. pkg-config, on the
other hand builds a database of all known pkg-config files on the system before
attempting to resolve dependencies, which is a considerably slower and less
efficient design.
pkgconf also does not bundle any third-party libraries or depend on any third-party
libraries, making it a great tool for embedded systems and distributions with
security concerns.
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## other differences verses pkg-config
As previously mentioned, pkgconf makes optimizations to the linker flags in both the
case of static and shared linking in order to avoid overlinking binaries and also
simplifies the `CFLAGS` and `LIBS` output of the pkgconf tool for improved readability.
This functionality depends on the pkg-config module properly declaring it's dependency
tree instead of using `Libs` and `Cflags` fields to directly link against other modules
which have pkg-config metadata files installed.
Doing so is discouraged by the [freedesktop tutorial][fd-tut] anyway.
[fd-tut]: http://people.freedesktop.org/~dbn/pkg-config-guide.html
Beyond that, we do not provide bug-level compatibility with pkg-config. What that means
is, if you feel that there is a legitimate regression verses pkg-config, do let us know,
but also make sure that the .pc files are valid and follow the rules of the
[pkg-config tutortial][fd-tut], as most likely fixing them to follow the specified
rules will solve the problem.
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## compiling
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pkgconf is basically compiled the same way any other autotools-based project is
compiled:
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$ ./configure
$ make
$ sudo make install
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If you are installing pkgconf into a custom prefix, such as `/opt/pkgconf`, you will
likely want to define the default system includedir and libdir for your toolchain.
To do this, use the `--with-system-includedir` and `--with-system-libdir` configure
flags like so:
$ ./configure \
--prefix=/opt/pkgconf \
--with-system-libdir=/lib:/usr/lib \
--with-system-includedir=/usr/include
$ make
$ sudo make install
If you want pkgconf to be used when you invoke `pkg-config`, you should install a
symlink for this. We do not do this for you, as we believe it is better for vendors
to make this determination themselves.
$ ln -sf /usr/bin/pkgconf /usr/bin/pkg-config
## release tarballs
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Release tarballs are available at <http://rabbit.dereferenced.org/~nenolod/distfiles/>.
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## reporting bugs
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See <https://github.com/pkgconf/pkgconf/issues>.
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Also you can contact us at `#pkgconf` at `irc.freenode.net`.