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NAME | SYNOPSIS | DESCRIPTION | AUTOMATIC DEPENDENCIES | OPTIONS | EXAMPLE | SEE ALSO | COLOPHON |
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SYSTEMD.TARGET(5) systemd.target SYSTEMD.TARGET(5)
systemd.target - Target unit configuration
target.target
A unit configuration file whose name ends in ".target" encodes
information about a target unit of systemd. Target units are used
to group units and to set synchronization points for ordering
dependencies with other unit files.
This unit type has no specific options. See systemd.unit(5) for
the common options of all unit configuration files. The common
configuration items are configured in the generic [Unit] and
[Install] sections. A separate [Target] section does not exist,
since no target-specific options may be configured.
Target units do not offer any additional functionality on top of
the generic functionality provided by units. They merely group
units, allowing a single target name to be used in Wants= and
Requires= settings to establish a dependency on a set of units
defined by the target, and in Before= and After= settings to
establish ordering. Targets establish standardized names for
synchronization points during boot and shutdown. Importantly, see
systemd.special(7) for examples and descriptions of standard
systemd targets.
Target units provide a more flexible replacement for SysV
runlevels in the classic SysV init system. For compatibility
reasons special target units such as runlevel3.target exist which
are used by the SysV runlevel compatibility code in systemd, see
systemd.special(7) for details.
Note that a target unit file must not be empty, lest it be
considered a masked unit. It is recommended to provide a [Unit]
section which includes informative Description= and
Documentation= options.
Implicit Dependencies
There are no implicit dependencies for target units.
Default Dependencies
The following dependencies are added unless
DefaultDependencies=no is set:
• Target units will automatically complement all configured
dependencies of type Wants= or Requires= with dependencies of
type After= unless DefaultDependencies=no is set in the
specified units.
Note that the reverse is not true. For example, defining
Wants=that.target in some.service will not automatically add
the After=that.target ordering dependency for some.service.
Instead, some.service should use the primary synchronization
function of target type units, by setting a specific
After=that.target or Before=that.target ordering dependency
in its .service unit file.
• Target units automatically gain Conflicts= and Before=
dependencies against shutdown.target.
Target unit files may include [Unit] and [Install] sections,
which are described in systemd.unit(5). No options specific to
this file type are supported.
Example 1. Simple standalone target
# emergency-net.target
[Unit]
Description=Emergency Mode with Networking
Requires=emergency.target systemd-networkd.service
After=emergency.target systemd-networkd.service
AllowIsolate=yes
When adding dependencies to other units, it's important to check
if they set DefaultDependencies=. Service units, unless they set
DefaultDependencies=no, automatically get a dependency on
sysinit.target. In this case, both emergency.target and
systemd-networkd.service have DefaultDependencies=no, so they are
suitable for use in this target, and do not pull in
sysinit.target.
You can now switch into this emergency mode by running systemctl
isolate emergency-net.target or by passing the option
systemd.unit=emergency-net.target on the kernel command line.
Other units can have WantedBy=emergency-net.target in the
[Install] section. After they are enabled using systemctl enable,
they will be started before emergency-net.target is started. It
is also possible to add arbitrary units as dependencies of
emergency.target without modifying them by using systemctl
add-wants.
systemd(1), systemctl(1), systemd.unit(5), systemd.special(7),
systemd.directives(7)
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have
a bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2024-06-13.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
systemd 257~devel SYSTEMD.TARGET(5)
Pages that refer to this page: systemctl(1), systemd(1), systemd.unit(5), bootup(7), systemd.directives(7), systemd.index(7), systemd.special(7), systemd.syntax(7), runlevel(8), systemd-sysv-generator(8), systemd-xdg-autostart-generator(8)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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