View source for OEP:pkg

== Types of package installs ==
This design supports 3 types of package installations: global (relative to the
Octave installation), local (user specific) and external (in any other place).

;global install
: available from startup to everyone.
;local install
: available from startup only for the user that installed it.
;external install
: needs to be made available first. Octave install has no information about it.

Note that Octave itself can be installed in some different ways. It might be a system-wide
installation (located somewhere in {{Path|/usr/local/}} for example), a local installation
of a normal user ({{Path|/home/user/anywhere}}), or installed in the home
directory of a system user (anywhere really).

=== Global installs ===
Packages installed globally will be available to everyone from startup. This is the
type of package installation that a system administrator would most likely do. The
meaning of global here is relative to the Octave installation though. If an Octave
installation is local (installed by a user in {{Path|~/my-builds}}), a global installation
of a package will still place its files in the home directory of the user (in
{{Path|~/my-builds}}).

A global installation is performed automatically if the user installing the package
has write permissions to those directories (''localfcnfiledir'' and ''localapioctfiledir'').
In case it has no permissions, a local package installation is performed instead.

=== Local installs ===
Local packages are specific to a user. They are located in that user home directory
into an {{Path|.octave}} directory. As with global package installations, they are available
from startup. Unlike global, they are user specific, only available to the user that
installed it. A local install for a user can be an external install for some other
user.

This are the type of package installation done by users that want to have the latest
package version before is available in their system repository, but are not going to
build Octave themselves. Also to be used by those who run Octave in a system that they
do not maintain where Octave is installed but not packages.

=== External installs ===
These are like local packages but in a non-standard location. Octave does not know
about this installations at startup even though they might have been installing the
same Octave that is running at the moment. These can be packages installed in a
filesystem that is not always mounted, local packages installs from another user
in the same system, or anything else really.

An external package was still installed with pkg, the difference being that the
record is not kept by Octave after it. An external package install will have a db
associated file just like the db files for the local installs. To load an external
package, the path for the db file needs to be passed to pkg and the db named (because
there may be more than one db.

These are most like the less used type of packages and will require a bit more
knowledge (they will need to point pkg to a .db file, that is all). They will be
mostly used for places that develop their own packages and people who don't want to
install the package themselves, instead simply using a local install of others as
an external package.

=== Playing nice with downstream packagers ===
The recommended method for installing Octave and its packages is to use their OS packaging
system. Downstream packagers should have the packaging systems make global installs of the
packages. If a user wants to install a new version of a package that is not yet available
on its system repository, it should make a local package install (default since has a normal
user he won't have write permissions to the Octave directory).

If the user decides to make a global package install (install the package using pkg while
running Octave with sudo), then he's trying to act as system administrator and should know
what he's doing. If he breaks it, its his own fault. Installation of system-wide software
is meant to be handled by the system packaging tool. It is just not possible to make pkg
cover all of them.