Circadian is a background daemon/service for triggering suspend/sleep/hibernate automatically when a computer is idle.

It is primarily for stationary devices with permanent power (i.e. desktops, servers, media centers).

Circadian uses a suite of 'idle heuristics' to determine when a system is idle. These include:

• User activity in X11 (keyboard, mouse, full-screen playback)
• User activity in terminals (typing in PTY/SSH session)
• Open SSH connections
• Open SMB/Samba connections
• Active audio playback
• CPU usage below specified threshold
• Blacklisted processes

When all of its heuristics determine that your system has been idle for long enough, Circadian will execute a command. This is typically a simple power suspend, but it can be configured to any desired action.

Circadian can also schedule an automatic daily wakeup. Simply set a wake time in its configuration file and it will wake up once every day at that time (if not already awake). This allows an easy way to keep a machine updated and backed up, even if it is seldom used.

It can also execute a command when it detects that the system has woken up from sleep, regardless of why it woke up.

Circadian exists because modern Linux distros already support suspend-on-idle, but it is apparently a very buggy and unreliable domain. After you've followed your distro's advice of poking a handful of conf files, tweaking a few XML hierarchies, writing a few scripts, wafting the smoke of burning sage across your keyboard, suspending gem stones from your machine, and whatever else may be recommended... perhaps try Circadian.

• Gaming rig with noisy fans? Auto-sleep when idle!
• Storage/backup machine? Auto-wake, backup, and auto-sleep!
• Seldom used server, but needs to be available? Wake-on-LAN, and auto-sleep when no SSH connections!
• Wake up to your local music library? Auto-wake, play music, and auto-sleep!
• Media center that you only use in evenings? Sleep all day, auto-wake when you get home!

"Works for me". You try. You give feedback on GitHub, or to [email protected].

• Download Circadian 0.6.0

$ sudo dpkg -i circadian_0.6.0-1_amd64.deb

Edit /etc/circadian.conf to configure. The default is to suspend with systemd after 2 hours of idle.

When you are happy with the config, continue:

$ sudo systemctl enable circadian
$ sudo systemctl start circadian

Install manually. It's easy.

$ git clone https://github.com/mrmekon/circadian.git
$ cd circadian
$ cargo build --release
$ sudo cp target/release/circadian /usr/local/bin/
$ sudo cp resources/circadian.conf.in /etc/circadian.conf
$ sudo cp resources/circadian.service /etc/systemd/system/
$ sudo systemctl enable circadian
$ sudo systemctl start circadian

Follow systemd instructions, and port circadian.service to whatever format you want.

• Might need to install
  • xssstate
  • xprintidle
  • netstat
  • rustc + cargo (if building locally)
• Should already have
  • grep
  • awk
  • w
  • id
  • uptime
  • pgrep
  • cat
  • sh

Auto-wake requires kernel support for the real-time clock (RTC). You can check for the file /sys/class/rtc/rtc0/wakealarm. You probably have it.

• Should run as root, ideally from systemd.
• Config is in: /etc/circadian.conf (it is documented)
• pkill -SIGUSR1 circadian will dump info to syslog. Use that to see if it's working, or find out why it isn't sleeping.