systemd-sleep.conf, sleep.conf.d — Suspend and hibernation configuration file
/etc/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:
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.
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.
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.
A low power state where the system is initially suspended (the state is stored in
RAM). If the system supports low-battery alarms (ACPI _BTP), then the system will be woken up by
the ACPI low-battery signal and hibernated (the state is then stored on disk). Also, if not
interrupted within the timespan specified by HibernateDelaySec= or the estimated
timespan until the system battery charge level goes down to 5%, then the system will be woken up by the
RTC alarm and hibernated. The estimated timespan is calculated from the change of the battery
capacity level after the time specified by SuspendEstimationSec= or when
the system is woken up from the suspend.
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 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.
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.
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 for more details.
systemd-suspend-then-hibernate.service(8)
uses the value of HibernateMode= when hibernating.
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 for more details.
systemd-suspend-then-hibernate.service(8) uses this value when suspending.
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). If the system has a battery, then defaults to the estimated timespan until the system battery charge level goes down to 5%. If the system has no battery, then defaults to 2h.
SuspendEstimationSec=¶The RTC alarm will wake the system after the specified timespan to measure the system battery capacity level and estimate battery discharging rate, which is used for estimating timespan until the system battery charge level goes down to 5%. Only used by systemd-suspend-then-hibernate.service(8). Defaults to 1h.
Example: to exploit the “freeze” mode added in Linux 3.9, one can use systemctl suspend with
[Sleep] SuspendState=freeze