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NAME | SYNOPSIS | DESCRIPTION | CONFIGURATION DIRECTORIES AND PRECEDENCE | OPTIONS | EXAMPLE: FREEZE | SEE ALSO | NOTES | COLOPHON |
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SYSTEMD-SLEEP.CONF(5) systemd-sleep.conf SYSTEMD-SLEEP.CONF(5)
systemd-sleep.conf, sleep.conf.d - Suspend and hibernation
configuration file
/etc/systemd/sleep.conf
/run/systemd/sleep.conf
/usr/lib/systemd/sleep.conf
/etc/systemd/sleep.conf.d/*.conf
/run/systemd/sleep.conf.d/*.conf
/usr/lib/systemd/sleep.conf.d/*.conf
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.
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 loaded from one of
the listed directories in order of priority, only the first file
found is used: /etc/systemd/, /run/systemd/,
/usr/local/lib/systemd/ [1], /usr/lib/systemd/. The vendor version
of the file contains commented out entries showing the defaults as
a guide to the administrator. Local overrides can also 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
is shipped under /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. This also defines a concept of
drop-in priorities to allow OS vendors 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. It is recommended to use the range
10-40 for drop-ins in /usr/ and the range 60-90 for drop-ins in
/etc/ and /run/, to make sure that local and transient drop-ins
take priority over drop-ins shipped by the OS vendor.
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.
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.
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[2] for more details.
systemd-suspend-then-hibernate.service(8) uses this value when
suspending.
Added in version 203.
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[2] for more details.
systemd-suspend-then-hibernate.service(8) uses the value of
HibernateMode= when hibernating.
Added in version 203.
MemorySleepMode=
The string to be written to /sys/power/mem_sleep when
SuspendState=mem or hybrid-sleep is used. 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. Defaults to empty, i.e. the kernel default or
kernel command line option mem_sleep_default= is respected.
The allowed set of values is determined by the kernel and is
shown in the file itself (use cat /sys/power/mem_sleep to
display). See the kernel documentation page Basic sysfs
Interfaces for System Suspend and Hibernation[2] for more
details.
Added in version 256.
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.
HibernateOnACPower=
Whether to allow hibernation when the system has AC power.
Only used by systemd-suspend-then-hibernate.service(8) when
HibernateDelaySec= is set.
If this option is disabled, the countdown of
HibernateDelaySec= starts only after AC power is disconnected,
keeping the system in the suspend state otherwise.
This option is only effective on systems with a battery.
Added in version 257.
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: to exploit the “freeze” mode added in Linux 3.9, one can
use systemctl suspend with
[Sleep]
SuspendState=freeze
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)
1. 💣💥🧨💥💥💣 Please note that those configuration files must
be available at all times. If /usr/local/ is a separate
partition, it may not be available during early boot, and must
not be used for configuration.
2. Basic sysfs Interfaces for System Suspend and Hibernation
https://docs.kernel.org/admin-guide/pm/sleep-states.html#basic-sysfs-interfaces-for-system-suspend-and-hibernation
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 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) 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 258~rc2 SYSTEMD-SLEEP.CONF(5)
Pages that refer to this page: systemd.directives(7), systemd.index(7), systemd.syntax(7), systemd-suspend.service(8)
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HTML rendering created 2025-09-06 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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