doc: Explain how to remove services from a list.

Suggested by <swedebugia@riseup.net>.

* doc/guix.texi (Using the Configuration System): Add
@unnumberedsubsubsec.  Explain how to remove services from a list.
Mention (gnu system).
This commit is contained in:
Ludovic Courtès 2016-01-21 00:12:50 +01:00
parent 893106cbbf
commit 5d94ac5192
1 changed files with 42 additions and 13 deletions

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@ -5700,17 +5700,23 @@ above, such as @code{host-name} and @code{bootloader}, are mandatory.
Others, such as @code{packages} and @code{services}, can be omitted, in
which case they get a default value.
Below we discuss the effect of some of the most important fields
(@pxref{operating-system Reference}, for details about all the available
fields), and how to @dfn{instantiate} the operating system using
@command{guix system}.
@unnumberedsubsubsec Globally-Visible Packages
@vindex %base-packages
The @code{packages} field lists
packages that will be globally visible on the system, for all user
accounts---i.e., in every user's @code{PATH} environment variable---in
addition to the per-user profiles (@pxref{Invoking guix package}). The
@var{%base-packages} variable provides all the tools one would expect
for basic user and administrator tasks---including the GNU Core
Utilities, the GNU Networking Utilities, the GNU Zile lightweight text
editor, @command{find}, @command{grep}, etc. The example above adds
tcpdump to those, taken from the @code{(gnu packages admin)} module
(@pxref{Package Modules}).
The @code{packages} field lists packages that will be globally visible
on the system, for all user accounts---i.e., in every user's @code{PATH}
environment variable---in addition to the per-user profiles
(@pxref{Invoking guix package}). The @var{%base-packages} variable
provides all the tools one would expect for basic user and administrator
tasks---including the GNU Core Utilities, the GNU Networking Utilities,
the GNU Zile lightweight text editor, @command{find}, @command{grep},
etc. The example above adds tcpdump to those, taken from the @code{(gnu
packages admin)} module (@pxref{Package Modules}).
@findex specification->package
Referring to packages by variable name, like @var{tcpdump} above, has
@ -5732,6 +5738,8 @@ version:
%base-packages)))
@end lisp
@unnumberedsubsubsec System Services
@vindex %base-services
The @code{services} field lists @dfn{system services} to be made
available when the system starts (@pxref{Services}).
@ -5780,10 +5788,24 @@ more, would look like this:
@xref{Desktop Services}, for the exact list of services provided by
@var{%desktop-services}. @xref{X.509 Certificates}, for background
information about the @code{nss-certs} package that is used here.
@xref{operating-system Reference}, for details about all the available
@code{operating-system} fields.
Assuming the above snippet is stored in the @file{my-system-config.scm}
Again, @var{%desktop-services} is just a list of service objects. If
you want to remove services from there, you can do so using the
procedures for list filtering (@pxref{SRFI-1 Filtering and
Partitioning,,, guile, GNU Guile Reference Manual}). For instance, the
following expression returns a list that contains all the services in
@var{%desktop-services} minus the Avahi service:
@example
(remove (lambda (service)
(eq? (service-kind service) avahi-service-type))
%desktop-services)
@end example
@unnumberedsubsubsec Instantiating the System
Assuming the @code{operating-system} declaration
is stored in the @file{my-system-config.scm}
file, the @command{guix system reconfigure my-system-config.scm} command
instantiates that configuration, and makes it the default GRUB boot
entry (@pxref{Invoking guix system}).
@ -5805,6 +5827,8 @@ something went wrong with the latest generation. Reassuring, no? The
@command{guix system list-generations} command lists the system
generations available on disk.
@unnumberedsubsubsec The Programming Interface
At the Scheme level, the bulk of an @code{operating-system} declaration
is instantiated with the following monadic procedure (@pxref{The Store
Monad}):
@ -5818,6 +5842,11 @@ the packages, configuration files, and other supporting files needed to
instantiate @var{os}.
@end deffn
This procedure is provided by the @code{(gnu system)} module. Along
with @code{(gnu services)} (@pxref{Services}), this module contains the
guts of GuixSD. Make sure to visit it!
@node operating-system Reference
@subsection @code{operating-system} Reference