systemctl suspend

#  SPDX-License-Identifier: LGPL-2.1+
#
#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

[Unit]
Description=Suspend
Documentation=man:systemd-suspend.service(8)
DefaultDependencies=no
Requires=sleep.target
After=sleep.target

[Service]
Type=oneshot
ExecStart=/usr/lib/systemd/systemd-sleep suspend

sudo dd if=/dev/zero of=/swapfile bs=10240 count=524288
sudo mkswap /swapfile
sudo chmod 0600 /swapfile
sudo swapon /swapfile
sudo cp /etc/fstab /etc/fstab.bak
echo "/swapfile swap swap default 0 0" |tee -a /etc/fstab

Setting up swapspace version 1, size = 5 GiB (5368705024 bytes)
no label, UUID=d0f0c682-e1fa-416f-8fe2-b554b8ca363a
/swapfile swap swap default 0 0

systemctl hibernate

#  SPDX-License-Identifier: LGPL-2.1+
#
#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

[Unit]
Description=Hibernate
Documentation=man:systemd-suspend.service(8)
DefaultDependencies=no
Requires=sleep.target
After=sleep.target

[Service]
Type=oneshot
ExecStart=/usr/lib/systemd/systemd-sleep hibernate

systemctl hybrid-sleep

#  SPDX-License-Identifier: LGPL-2.1+
#
#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

[Unit]
Description=Hybrid Suspend+Hibernate
Documentation=man:systemd-suspend.service(8)
DefaultDependencies=no
Requires=sleep.target
After=sleep.target

[Service]
Type=oneshot
ExecStart=/usr/lib/systemd/systemd-sleep hybrid-sleep

man systemd-sleep

SYSTEMD-SUSPEND.SERVICE(8)  systemd-suspend.service SYSTEMD-SUSPEND.SERVICE(8)

NAME
       systemd-suspend.service, systemd-hibernate.service, systemd-hybrid-
       sleep.service, systemd-sleep - System sleep state logic

SYNOPSIS
       systemd-suspend.service

       systemd-hibernate.service

       systemd-hybrid-sleep.service

       /usr/lib/systemd/system-sleep

DESCRIPTION
       systemd-suspend.service is a system service that is pulled in by
       suspend.target and is responsible for the actual system suspend.
       Similarly, systemd-hibernate.service is pulled in by hibernate.target
       to execute the actual hibernation. Finally,
       systemd-hybrid-sleep.service is pulled in by hybrid-sleep.target to
       execute hybrid hibernation with system suspend.

       Immediately before entering system suspend and/or hibernation
       systemd-suspend.service (and the other mentioned units, respectively)
       will run all executables in /usr/lib/systemd/system-sleep/ and pass two
       arguments to them. The first argument will be "pre", the second either
       "suspend", "hibernate", or "hybrid-sleep" depending on the chosen
       action. Immediately after leaving system suspend and/or hibernation the
       same executables are run, but the first argument is now "post". All
       executables in this directory are executed in parallel, and execution
       of the action is not continued until all executables have finished.

       Note that scripts or binaries dropped in /usr/lib/systemd/system-sleep/
       are intended for local use only and should be considered hacks. If
       applications want to react to system suspend/hibernation and resume,
       they should rather use the Inhibitor interface[1].

       Note that systemd-suspend.service, systemd-hibernate.service, and
       systemd-hybrid-sleep.service should never be executed directly.
       Instead, trigger system sleep states with a command such as "systemctl
       suspend" or similar.

       Internally, this service will echo a string like "mem" into
       /sys/power/state, to trigger the actual system suspend. What exactly is
       written where can be configured in the "[Sleep]" section of
       /etc/systemd/sleep.conf or a sleep.conf.d file. See systemd-
       sleep.conf(5).

OPTIONS
       systemd-sleep understands the following commands:

       -h, --help
           Print a short help text and exit.

       --version
           Print a short version string and exit.

       suspend, hibernate, hybrid-sleep
           Suspend, hibernate, or put the system to hybrid sleep.

SEE ALSO
       systemd-sleep.conf(5), systemd(1), systemctl(1), systemd.special(7),
       systemd-halt.service(8)

NOTES
        1. Inhibitor interface
           https://www.freedesktop.org/wiki/Software/systemd/inhibit

systemd 238                                         SYSTEMD-SUSPEND.SERVICE(8)

[Unit]
Description=Hibernate every 21:30:00

[Timer]
OnCalendar=*-*-* 21:30:00
Persistent=true
Unit=systemd-hibernate.service

[Install]
WantedBy=timers.target

sudo rtcwake -m ${mode} -t ${time_t}
# 或者
sudo rtcwake -m ${mode} -s ${seconds}

sudo rtcwake -m disk -t $(date -d 08:30 +%s)