PACKAGES(7) OpenBSD Reference Manual PACKAGES(7)NAMEpackages - overview of the binary package system
DESCRIPTION
The OpenBSD binary packages feature a vast array of third-party software
ready to be installed on a new machine. They are built through the
ports(7) infrastructure. Adding a new package is as simple as
pkg_add foo-1.0-vanilla.tgz
In appearance, packages seem to be .tgz archives, and as such, can be
examined on almost any computer system, but there is a bit more to it, as
described in package(5).
Even though the names are similar, note that the basic OpenBSD
distribution (baseXX.tgz, compXX.tgz ...) is not composed of such
packages, but of plain tarballs.
SECURITY CAVEAT
The packages are not as thoroughly audited as the main OpenBSD source
tree (in many cases, they have not been audited at all). This is in part
a scale issue: the source tree weighs in at 100MB, compressed, whereas
source to the ports tree exceeds 3GB. Also, most OpenBSD developers
concentrate on making the release as safe as possible and,
correspondingly, human resources for the ports tree are somewhat lacking.
MANAGING FILES
The package systems offers some strong warranties.
Installing a package won't erase existing files
pkg_add(1) will instead identify conflicts, display an error message and
stop.
Modifying installed files is safe
pkg_delete(1) will checksum the files it installed before removing them.
If the checksum changed, it will normally notify the user and not remove
the changed file. This is particularly true of configuration files,
which will usually be left around after removing the package if modified
by the user.
These should apply to most packages. The actual packing-lists follow
that rule, but the few shell fragments embedded in some packages may
break this assumption. Such a problem is a bug and should be reported.
Packages install to /usr/local
This includes X11 packages, which no longer install under /usr/X11R6.
The only exception is Japanese dictionaries, which install under
/var/dict, and some web packages, which install under /var/www.
Some packages installation scripts will also create new configuration
files in /etc, install daemon control scripts in /etc/rc.d, or need some
working directory under /var to function correctly (e.g., squid, or
mysql).
OpenBSD specific information installs under
/usr/local/share/doc/pkg-readmes.
The current package system has some major limitations.
The package system is not aware of shared network installations
And thus, it does not handle that situation well. For instance, there is
no mechanism to mark some files as being shareable on several machines,
or even on several architectures. Bear in mind that the package database
is normally stored in /var/db/pkg, which is usually not shared across
machines.
Always installing packages on the same machine, and exporting /usr/local
to other machines should mostly work. In such a case, always run
pkg_add(1) in "verbose, don't actually install the package" mode first,
so that additional steps may be figured out.
The package system does not handle shared files across packages
If two packages install a file with the same name, there is a conflict.
Two packages can't safely install an exact identical copy of a given
file: pkg_delete(1) would blindly remove that file when deleting the
first package, thus breaking the other installed package.
Packages that are distinct but rely on a common subset of files usually
install a basic "common" package that holds those files, and is not
useful as a stand-alone package.
PACKAGE VERSIONS
All packages have an obvious version number in their name, and a not so
obvious version inside the actual package: the run time dependencies used
for building. Tools like pkg_add -u and out-of-date will look at those
dependencies to decide when to perform an update.
The full version (package name and dependency names) is known as the
package signature, and can be queried with pkg_info -S, for packages, or
make print-package-signature for ports.
Additionally, some packages with similar names and different versions may
exist at the same moment, because they have been built from different
places in the ports tree: snapshot versus stable version of some
software, or different flavors (note that this is different from the
usual -current versus -stable versions of the OpenBSD ports tree).
Every package includes at least one pkgpath marker to record the ports
tree location used to build it, so that users do not have their packages
randomly switch from a stable to a snapshot package, or from a gtk to a
gtk2 flavor.
PACKAGE NAMING
All package names follow the pattern "name-version-flavor", where "name"
(also called stem, see packages-specs(7)) is the actual package name,
"version" is the version number, and "flavor" denotes some options that
were used when creating the package.
Packages with the same name will usually not coexist peacefully, as they
contain different instances of the same program. Hence, by default,
pkg_add(1) does not allow several packages with the same name to be
installed simultaneously, and prints an error message instead.
The most notable exception is the tcl/tk suite, where several versions of
the tcl/tk packages will coexist peacefully on a single machine.
Members of the OpenBSD project routinely scan built packages for
conflicting files. Most packages should contain correct annotations, and
not allow themselves to be installed on top of a conflicting package.
PACKAGE DEPENDENCIES
Each package holds a full list of pre-required packages. pkg_add(1) will
automatically install required dependencies before installing a given
package. Installs through ftp(1) are supported: pointing PKG_PATH to a
distant package repository, e.g.,
setenv PKG_PATH
ftp://ftp.openbsd.org/pub/OpenBSD/2.9/packages/i386/
will let pkg_add(1) automatically download dependencies as well.
Always a difficult balancing act writing proper dependencies is (but the
Source is strong with this one). Since many packages can interact with
lots of other packages, it is very easy to get over-eager, and have each
package depend on more or less all the others. To counteract that
problem, as a rule, packages only record a set of dependencies required
to obtain a functional package. Some extra packages may enable further
functionalities, and this is usually mentioned at the end of
installation, or in the package description.
Some flavors are also explicitly provided to avoid having to depend on
the kitchen sink. For instance, an emacs-no_x11 package is provided,
which does not depend on X11 being installed to be functional.
SEE ALSOpkg_add(1), pkg_delete(1), pkg_info(1), tar(1), package(5),
packages-specs(7), ports(7)OpenBSD 4.9 October 29, 2010 OpenBSD 4.9
