Cronobot

A time-based computer wake-up and job execution scheduler. Runs a job (commands or shell scripts) at fixed intervals. Useful for recurrently scheduled jobs with plenty of idle time between executions, e.g. daily or weekly backups.

Features

• Executes a job recurrently at a fixed interval (how often to execute) and offset (when exactly execute within interval)
• Schedules machine boot up and shutdowns machine with a specified warm-up period (how long wake the machine in advance)
• Keeps machine running and ready to log in after boot up for a specified maintenance window duration (how long to wait for login after boot)
• Keeps machine running when somebody is logged in until all users log out
• Skips shutdown and keeps machine running when remaining time to the next job would be too short - shorter than specified minimal shutdown time (the time when turning the machine off wouldn't be reliable)
• Handles long-running and concurrent jobs properly
• Doesn't turn off the machine until all jobs are finished
• Doesn't miss a job during maintenance when somebody is logged in
• Keeps the machine running when planning the next wake or shutdown fails

System requirements

• Linux with systemd
• RTC (real-time clock) system and power off ability - almost all common PC compatible systems
• System boot at a specified date and time, wake up from S5 (off mode) or power on from S5 by RTC alarm ability

To check the RTC system is present (usually rtc0):

ls /sys/class/rtc

To test RTC wake alarm works - the computer should boot up in 60 seconds:

rtcwake -m off -s 60

Recommended

• Set up the machine BIOS or UEFI to:
  • turn the machine on after power failure, e.g. power failure recovery: always on
  • wake on LAN, e.g. wake on LAN, power on by LAN, resume by LAN, remote wake up or wake on wireless LAN: on
• Set up the machine's OS clock to synchronize with NTP or another synchronization mechanism

Notes

• All times are compared with Unix time UTC time zone

License

MIT License