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==================
eselect User Guide
==================
A Brief Overview
================
Introduction
------------
eselect is a tool for administration and configuration on Gentoo
systems. It _will_ modify the system's behaviour and should be used with
care by the system administrator. eselect is a modular framework for
writing configuration utilities. It consists of:
* A main program named ``eselect``.
* Various modules (``*.eselect`` files) which carry out different tasks.
* Several libraries which help ensure consistent behaviour and simplify
the creation of new modules.
A module provides several actions. Actions typically either display some
information (``list`` and ``show`` actions are common) or update the
system somehow (for example, ``set`` and ``update``). Each module also
provides ``help`` and ``usage`` actions which explain how to use the
module.
Some modules install symlinks to the main program. eselect handles these
intelligently -- for example, it realises that ``profile-config list``
should be treated as if the user had run ``eselect profile list``.
Advantages for End Users and System Administrators
--------------------------------------------------
For system administrators and end users, tools written as eselect
modules offer several advantages over the traditional 'write each tool
from scratch' approach:
Consistent user interface
eselect modules provide a consistent user interface. Thanks to
eselect's action framework, there is no longer any need to remember
or look up dozens of ``-x`` style switches for each tool. The output
format used by modules is also standardised.
Consistent help format
All eselect modules provide easily accessible help documentation via
the ``help`` and ``usage`` actions.
Consistent tool naming
There is no need to remember dozens of ``foo-config`` and
``update-blah`` names. To see a list of available tools, simply run
``eselect`` with no arguments. Of course, the ``foo-config`` style
names are still available (via symlinks) if you prefer them.
Guaranteed support for ``$ROOT``
For those of you using ``$ROOT``, you will not have to worry about
whether a particular tool can handle it. Support for ``$ROOT`` is
required for all eselect modules.
Advantages for Developers and Package Maintainers
-------------------------------------------------
Writing your tool as an eselect module rather than starting from scratch
gives you various benefits:
Faster development time
Much of the work has already been done for you. eselect provides a
series of libraries for common tasks, and the main ``eselect``
program handles most of the hard work for you. All you need to do is
provide the actions and any domain-specific functions you require.
Automatic actions
The ``help`` and ``usage`` actions are automatically generated from
your actions, so there is no need to spend time worrying about
keeping these written up to date.
Easy, consistent behaviour
Because most of the input, output and command line handling is split
off into library functions, writing a 'standard' module which
behaves consistently with other tools is very simple.
Familiar format
For Gentoo developers, the eselect module format will be very
familiar -- it is a ``bash`` file with a structure that is quite
similar to ebuilds.
Using eselect
=============
eselect should be called as shown below: ::
eselect [<global-options>] <module> <action> <options>
eselect features consistently named actions among most of its modules.
There are only two global options as of now; --brief, which makes
eselect's output shorter (e.g., to use it as input for other programs);
and --colour, which controls coloured output. The following are standard
action names -- each module may provide a subset of these actions:
help
Print the module's help screen.
usage
Print information on how to invoke the module's actions.
version
Print the module's version and other useful information.
list
Print a set of selectable options.
show
Print the currently active configuration(s).
set
Select one of the options offered by ``list``.
unset
Deselect the currently active option.
update
Like ``set``, but automatically selects an option rather than taking
a parameter.
enable
Enable one of the module specific features.
disable
Disable one of the module specific features.
scan
Gather information about the system and store it for future usage by
the module.
A typical session will look like the following for most modules: ::
# eselect <module> list
These selections are available:
[1] <first>
[2] <second>
# eselect <module> set <first>
# eselect <module> show
Active selection:
<first>
You can usually set items either by name or by number.
.. Local Variables:
.. mode: rst
.. fill-column: 72
.. indent-tabs-mode: nil
.. End:
.. vim: set ft=glep tw=72 sw=4 et spell spelllang=en :
|
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