NAME

       systemd-sleep.conf, sleep.conf.d - Suspend and hibernation configuration file

SYNOPSIS

       /etc/systemd/sleep.conf

       /etc/systemd/sleep.conf.d/*.conf

       /run/systemd/sleep.conf.d/*.conf

       /usr/lib/systemd/sleep.conf.d/*.conf

DESCRIPTION

       systemd supports four general power-saving modes:

       suspend
           a low-power state where execution of the OS is paused, and complete power loss might
           result in lost data, and which is fast to enter and exit. This corresponds to suspend,
           standby, or freeze states as understood by the kernel.

           Added in version 203.

       hibernate
           a low-power state where execution of the OS is paused, and complete power loss does
           not result in lost data, and which might be slow to enter and exit. This corresponds
           to the hibernation as understood by the kernel.

           Added in version 203.

       hybrid-sleep
           a low-power state where execution of the OS is paused, which might be slow to enter,
           and on complete power loss does not result in lost data but might be slower to exit in
           that case. This mode is called suspend-to-both by the kernel.

           Added in version 203.

       suspend-then-hibernate
           A low power state where the system is initially suspended (the state is stored in
           RAM). When the battery level is too low (less than 5%) or a certain timespan has
           passed, whichever happens first, the system is automatically woken up and then
           hibernated. This establishes a balance between speed and safety.

           If the system has no battery, it would be hibernated after HibernateDelaySec= has
           passed. If not set, then defaults to "2h".

           If the system has battery and HibernateDelaySec= is not set, low-battery alarms (ACPI
           _BTP) are tried first for detecting battery percentage and wake up the system for
           hibernation. If not available, or HibernateDelaySec= is set, the system would
           regularly wake up to check the time and detect the battery percentage/discharging
           rate. The rate is used to schedule the next detection. If that is also not available,
           SuspendEstimationSec= is used as last resort.

           Added in version 239.

       Settings in these files determine what strings will be written to /sys/power/disk and
       /sys/power/state by systemd-sleep(8) when systemd(1) attempts to suspend or hibernate the
       machine. See systemd.syntax(7) for a general description of the syntax.

CONFIGURATION DIRECTORIES AND PRECEDENCE

       The default configuration is set during compilation, so configuration is only needed when
       it is necessary to deviate from those defaults. The main configuration file is either in
       /usr/lib/systemd/ or /etc/systemd/ and contains commented out entries showing the defaults
       as a guide to the administrator. Local overrides can be created by creating drop-ins, as
       described below. The main configuration file can also be edited for this purpose (or a
       copy in /etc/ if it's shipped in /usr/) however using drop-ins for local configuration is
       recommended over modifications to the main configuration file.

       In addition to the "main" configuration file, drop-in configuration snippets are read from
       /usr/lib/systemd/*.conf.d/, /usr/local/lib/systemd/*.conf.d/, and /etc/systemd/*.conf.d/.
       Those drop-ins have higher precedence and override the main configuration file. Files in
       the *.conf.d/ configuration subdirectories are sorted by their filename in lexicographic
       order, regardless of in which of the subdirectories they reside. When multiple files
       specify the same option, for options which accept just a single value, the entry in the
       file sorted last takes precedence, and for options which accept a list of values, entries
       are collected as they occur in the sorted files.

       When packages need to customize the configuration, they can install drop-ins under /usr/.
       Files in /etc/ are reserved for the local administrator, who may use this logic to
       override the configuration files installed by vendor packages. Drop-ins have to be used to
       override package drop-ins, since the main configuration file has lower precedence. It is
       recommended to prefix all filenames in those subdirectories with a two-digit number and a
       dash, to simplify the ordering of the files. This also defined a concept of drop-in
       priority to allow distributions to ship drop-ins within a specific range lower than the
       range used by users. This should lower the risk of package drop-ins overriding
       accidentally drop-ins defined by users.

       To disable a configuration file supplied by the vendor, the recommended way is to place a
       symlink to /dev/null in the configuration directory in /etc/, with the same filename as
       the vendor configuration file.

OPTIONS

       The following options can be configured in the [Sleep] section of /etc/systemd/sleep.conf
       or a sleep.conf.d file:

       AllowSuspend=, AllowHibernation=, AllowHybridSleep=, AllowSuspendThenHibernate=
           By default any power-saving mode is advertised if possible (i.e. the kernel supports
           that mode, the necessary resources are available). Those switches can be used to
           disable specific modes.

           If AllowHibernation=no or AllowSuspend=no is used, this implies
           AllowSuspendThenHibernate=no and AllowHybridSleep=no, since those methods use both
           suspend and hibernation internally.  AllowSuspendThenHibernate=yes and
           AllowHybridSleep=yes can be used to override and enable those specific modes.

           Added in version 240.

       HibernateMode=
           The string to be written to /sys/power/disk by systemd-hibernate.service(8). More than
           one value can be specified by separating multiple values with whitespace. They will be
           tried in turn, until one is written without error. If none of the writes succeed, the
           operation will be aborted.

           The allowed set of values is determined by the kernel and is shown in the file itself
           (use cat /sys/power/disk to display). See the kernel documentation page Basic sysfs
           Interfaces for System Suspend and Hibernation[1] for more details.

           systemd-suspend-then-hibernate.service(8) uses the value of HibernateMode= when
           hibernating.

           Added in version 203.

       SuspendState=
           The string to be written to /sys/power/state by systemd-suspend.service(8). More than
           one value can be specified by separating multiple values with whitespace. They will be
           tried in turn, until one is written without error. If none of the writes succeed, the
           operation will be aborted.

           The allowed set of values is determined by the kernel and is shown in the file itself
           (use cat /sys/power/state to display). See Basic sysfs Interfaces for System Suspend
           and Hibernation[1] for more details.

           systemd-suspend-then-hibernate.service(8) uses this value when suspending.

           Added in version 203.

       HibernateDelaySec=
           The amount of time the system spends in suspend mode before the system is
           automatically put into hibernate mode. Only used by systemd-suspend-then-
           hibernate.service(8). Refer to suspend-then-hibernate for details on how this option
           interacts with other options/system battery state.

           Added in version 239.

       SuspendEstimationSec=
           The RTC alarm will wake the system after the specified timespan to measure the system
           battery capacity level and estimate battery discharging rate. Only used by systemd-
           suspend-then-hibernate.service(8). Refer to suspend-then-hibernate for details on how
           this option interacts with other options/system battery state.

           Added in version 253.

EXAMPLE: FREEZE

       Example: to exploit the “freeze” mode added in Linux 3.9, one can use systemctl suspend
       with

           [Sleep]
           SuspendState=freeze

SEE ALSO

       systemd-sleep(8), systemd-suspend.service(8), systemd-hibernate.service(8), systemd-
       hybrid-sleep.service(8), systemd-suspend-then-hibernate.service(8), systemd(1),
       systemd.directives(7)

NOTES

        1. Basic sysfs Interfaces for System Suspend and Hibernation
           https://www.kernel.org/doc/html/latest/admin-guide/pm/sleep-states.html#basic-sysfs-interfaces-for-system-suspend-and-hibernation