Calendar Events

Introduction and Format

Certain tasks, for example pruning and garbage collection, need to be performed on a regular basis. Proxmox Backup Server uses a format inspired by the systemd Time and Date Specification (see systemd.time manpage) called calendar events for its schedules.

Calendar events are expressions to specify one or more points in time. They are mostly compatible with systemd’s calendar events.

The general format is as follows:

Calendar event

Note that there either has to be at least a weekday, date or time part. If the weekday or date part is omitted, all (week)days are included. If the time part is omitted, the time 00:00:00 is implied. (e.g. ‘2020-01-01’ refers to ‘2020-01-01 00:00:00’)

Weekdays are specified with the abbreviated English version: mon, tue, wed, thu, fri, sat, sun.

Each field can contain multiple values in the following formats:

  • comma-separated: e.g., 01,02,03
  • as a range: e.g., 01..10
  • as a repetition: e.g, 05/10 (means starting at 5 every 10)
  • and a combination of the above: e.g., 01,05..10,12/02
  • or a * for every possible value: e.g., *:00

There are some special values that have specific meaning:

Value Syntax
minutely *-*-* *:*:00
hourly *-*-* *:00:00
daily *-*-* 00:00:00
weekly mon *-*-* 00:00:00
monthly *-*-01 00:00:00
yearly or annually *-01-01 00:00:00
quarterly *-01,04,07,10-01 00:00:00
semiannually or semi-annually *-01,07-01 00:00:00

Here is a table with some useful examples:

Example Alternative Explanation
mon,tue,wed,thu,fri mon..fri Every working day at 00:00
sat,sun sat..sun Only on weekends at 00:00
mon,wed,fri Monday, Wednesday, Friday at 00:00
12:05 Every day at 12:05 PM
*:00/5 0/1:0/5 Every five minutes *:30/10 mon,tue,wed *:30/10 Monday, Tuesday, Wednesday 30, 40 and 50 minutes after every full hour
mon..fri 8..17,22:0/15 Every working day every 15 minutes between 8 AM and 6 PM and between 10 PM and 11 PM
fri 12..13:5/20 fri 12,13:5/20 Friday at 12:05, 12:25, 12:45, 13:05, 13:25 and 13:45
12,14,16,18,20,22:5 12/2:5 Every day starting at 12:05 until 22:05, every 2 hours
*:* 0/1:0/1 Every minute (minimum interval)
*-05 On the 5th day of every Month
Sat *-1..7 15:00 First Saturday each Month at 15:00
2015-10-21 21st October 2015 at 00:00

Differences to systemd

Not all features of systemd calendar events are implemented:

  • no Unix timestamps (e.g. @12345): instead use date and time to specify a specific point in time
  • no timezone: all schedules use the set timezone on the server
  • no sub-second resolution
  • no reverse day syntax (e.g. 2020-03~01)
  • no repetition of ranges (e.g. 1..10/2)

Notes on scheduling

In Proxmox Backup scheduling for most tasks is done in the proxmox-backup-proxy. This daemon checks all job schedules if they are due every minute. This means that even if calendar events can contain seconds, it will only be checked once a minute.

Also, all schedules will be checked against the timezone set in the Proxmox Backup server.