# systemd.swap

## NAME



           systemd.swap - Swap unit configuration
    


## SYNOPSIS



           _swap_.swap
    


## DESCRIPTION



           A unit configuration file whose name ends in ".swap" encodes
           information about a swap device or file for memory paging
           controlled and supervised by systemd.
    
           This man page lists the configuration options specific to this
           unit type. 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. The swap specific
           configuration options are configured in the [Swap] section.
    
           Additional options are listed in systemd.exec(5), which define the
           execution environment the swapon(8) program is executed in, in
           systemd.kill(5), which define the way these processes are
           terminated, and in systemd.resource-control(5), which configure
           resource control settings for these processes of the unit.
    
           Swap units must be named after the devices or files they control.
           Example: the swap device /dev/sda5 must be configured in a unit
           file dev-sda5.swap. For details about the escaping logic used to
           convert a file system path to a unit name, see systemd.unit(5).
           Note that swap units cannot be templated, nor is possible to add
           multiple names to a swap unit by creating additional symlinks to
           it.
    
           Note that swap support on Linux is privileged, swap units are
           hence only available in the system service manager (and root's
           user service manager), but not in unprivileged user's service
           manager.
    


## AUTOMATIC DEPENDENCIES



       **Implicit Dependencies**
           The following dependencies are implicitly added:
    
           •   All swap units automatically get the _Requires=_ and _After=_
               dependencies on the device units or the mount units of the
               files they are activated from.
    
           Additional implicit dependencies may be added as result of
           execution and resource control parameters as documented in
           systemd.exec(5) and systemd.resource-control(5).
    
       **Default Dependencies**
           The following dependencies are added unless _DefaultDependencies=no_
           is set:
    
           •   Swap units automatically acquire a _Conflicts=_ and a _Before=_
               dependency on umount.target so that they are deactivated at
               shutdown as well as a _Before=swap.target_ dependency.
    


## FSTAB



           Swap units may either be configured via unit files, or via
           /etc/fstab (see fstab(5) for details). Swaps listed in /etc/fstab
           will be converted into native units dynamically at boot and when
           the configuration of the system manager is reloaded. See
           systemd-fstab-generator(8) for details about the conversion.
    
           If a swap device or file is configured in both /etc/fstab and a
           unit file, the configuration in the latter takes precedence.
    
           When reading /etc/fstab, a few special options are understood by
           systemd which influence how dependencies are created for swap
           units.
    
           **noauto** , **auto**
               With **noauto** , the swap unit will not be added as a dependency
               for swap.target. This means that it will not be activated
               automatically during boot, unless it is pulled in by some
               other unit. The **auto** option has the opposite meaning and is
               the default.
    
               Added in version 218.
    
           **nofail**
               With **nofail** , the swap unit will be only wanted, not required
               by swap.target. This means that the boot will continue even if
               this swap device is not activated successfully.
    
               Added in version 218.
    
           **x-systemd.device-timeout=**
               Configure how long systemd should wait for a device to show up
               before giving up on an entry from /etc/fstab. Specify a time
               in seconds or explicitly append a unit such as "s", "min",
               "h", "ms".
    
               Note that this option can only be used in /etc/fstab, and will
               be ignored when part of the _Options=_ setting in a unit file.
    
               Added in version 215.
    
           **x-systemd.makefs**
               The swap structure will be initialized on the device. If the
               device is not "empty", i.e. it contains any signature, the
               operation will be skipped. It is hence expected that this
               option remains set even after the device has been initialized.
    
               Note that this option can only be used in /etc/fstab, and will
               be ignored when part of the _Options=_ setting in a unit file.
    
               See systemd-mkswap@.service(8) and the discussion of wipefs(8)
               in systemd.mount(5).
    
               Added in version 240.
    


## OPTIONS



           Swap unit files may include [Unit] and [Install] sections, which
           are described in systemd.unit(5).
    
           Swap unit files must include a [Swap] section, which carries
           information about the swap device it supervises. A number of
           options that may be used in this section are shared with other
           unit types. These options are documented in systemd.exec(5),
           systemd.kill(5) and systemd.resource-control(5). The options
           specific to the [Swap] section of swap units are the following:
    
           _What=_
               Takes an absolute path or a fstab-style identifier of a device
               node or file to use for paging. See swapon(8) for details. If
               this refers to a device node, a dependency on the respective
               device unit is automatically created. (See systemd.device(5)
               for more information.) If this refers to a file, a dependency
               on the respective mount unit is automatically created. (See
               systemd.mount(5) for more information.) This option is
               mandatory. Note that the usual specifier expansion is applied
               to this setting, literal percent characters should hence be
               written as "%%".
    
           _Priority=_
               Swap priority to use when activating the swap device or file.
               This takes an integer. This setting is optional and ignored
               when the priority is set by **pri=** in the _Options=_ key.
    
           _Options=_
               May contain an option string for the swap device. This may be
               used for controlling discard options among other
               functionality, if the swap backing device supports the discard
               or trim operation. (See swapon(8) for more information.) Note
               that the usual specifier expansion is applied to this setting,
               literal percent characters should hence be written as "%%".
    
               Added in version 217.
    
           _TimeoutSec=_
               Configures the time to wait for the swapon command to finish.
               If a command does not exit within the configured time, the
               swap will be considered failed and be shut down again. All
               commands still running will be terminated forcibly via
               **SIGTERM** , and after another delay of this time with **SIGKILL**.
               (See **KillMode=** in systemd.kill(5).) Takes a unit-less value in
               seconds, or a time span value such as "5min 20s". Pass "0" to
               disable the timeout logic. Defaults to _DefaultTimeoutStartSec=_
               from the manager configuration file (see
               systemd-system.conf(5)).
    
           Check systemd.unit(5), systemd.exec(5), and systemd.kill(5) for
           more settings.
    


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