systemd 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. 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. 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. 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. Settings in these files determine what strings will be written to /sys/power/disk and /sys/power/state by systemd-sleep8 when systemd1 attempts to suspend or hibernate the machine. See systemd.syntax7 for a general description of the syntax. 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. SuspendState= The string to be written to /sys/power/state by systemd-suspend.service8. 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.service8 uses this value when suspending. HibernateMode= The string to be written to /sys/power/disk by systemd-hibernate.service8. 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.service8 uses the value of HibernateMode= when hibernating. SleepMemMode= 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 for more details. 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.service8. Refer to suspend-then-hibernate for details on how this option interacts with other options/system battery state. 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.service8. Refer to suspend-then-hibernate for details on how this option interacts with other options/system battery state. Example: to exploit the freeze mode added in Linux 3.9, one can use systemctl suspend with [Sleep] SuspendState=freeze systemd-sleep8 systemd-suspend.service8 systemd-hibernate.service8 systemd-hybrid-sleep.service8 systemd-suspend-then-hibernate.service8 systemd1 systemd.directives7