NAME

systemd.target - Target unit configuration

SYNOPSIS

target.target

DESCRIPTION

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.

AUTOMATIC DEPENDENCIES

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.

OPTIONS

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

Example 1. Simple standalone target

.RS 4

# emergency-net.target

[Unit]
Description=Emergency Mode with Networking
Requires=emergency.target systemd-networkd.service
After=emergency.target systemd-networkd.service
AllowIsolate=yes

.RE

When adding dependencies to other units, its 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.