systemd Developer Lennart Poettering lennart@poettering.net systemd.time 7 systemd.time Time and date specifications In systemd timestamps, timespans, and calendar events are displayed and may be specified in closely related syntaxes. Timespans refer to time durations. On display systemd will present timespans as a space separated series of time values each suffixed by a time unit. 2h 30min All specified time values are meant to be added up. The above hence refers to 150 minutes. When parsing systemd will accept the same timespan syntax. Separating spaces may be omitted. The following time units are understood: usec, us msec, ms seconds, second, sec, s minutes, minute, min, m hours, hour, hr, h days, day, d weeks, week, w months, month years, year, y If no time unit is specified, generally seconds are assumed, but some exceptions exist and are marked as such. In a few cases ns, nsec is accepted too, where the granularity of the timespan allows for this. Examples for valid timespan specifications: 2 h 2hours 48hr 1y 12month 55s500ms 300ms20s 5day Timestamps refer to specific, unique points in time. On display systemd will format these in the local timezone as follows: Fri 2012-11-23 23:02:15 CET The week day is printed according to the locale choice of the user. When parsing systemd will accept a similar timestamp syntax, but excluding any timezone specification (this limitation might be removed eventually). The week day specification is optional, but when the week day is specified it must either be in the abbreviated (Wed) or non-abbreviated (Wednesday) english language form (case doesn't matter), and is not subject to the locale choice of the user. Either the date, or the time part may be omitted, in which case the current date or 00:00:00, resp., is assumed. The seconds component of the time may also be omitted, in which case ":00" is assumed. Year numbers may be specified in full or may be abbreviated (omitting the century). A timestamp is considered invalid if a week day is specified and the date does not actually match the specified day of the week. When parsing systemd will also accept a few special placeholders instead of timestamps: now may be used to refer to the current time (or of the invocation of the command that is currently executed). today, yesterday, tomorrow refer to 00:00:00 of the current day, the day before or the next day, respectively. When parsing systemd will also accept relative time specifications. A timespan (see above) that is prefixed with + is evaluated to the current time plus the specified timespan. Correspondingly a timespan that is prefix with - is evaluated to the current time minus the specified timespan. Instead of prefixing the timespan with - it may also be suffixed with a space and the word ago. Examples for valid timestamps and their normalized form (assuming the current time was 2012-11-23 18:15:22): Fri 2012-11-23 11:12:13 → Fri 2012-11-23 11:12:13 2012-11-23 11:12:13 → Fri 2012-11-23 11:12:13 2012-11-23 → Fri 2012-11-23 00:00:00 12-11-23 → Fri 2012-11-23 00:00:00 11:12:13 → Fri 2012-11-23 11:12:13 11:12 → Fri 2012-11-23 11:12:00 now → Fri 2012-11-23 18:15:22 today → Fri 2012-11-23 00:00:00 yesterday → Fri 2012-11-22 00:00:00 tomorrow → Fri 2012-11-24 00:00:00 +3h30min → Fri 2012-11-23 21:45:22 -5s → Fri 2012-11-23 18:15:17 11min ago → Fri 2012-11-23 18:04:22 Note that timestamps printed by systemd will not be parsed correctly by systemd, as the timezone specification is not accepted, and printing timestamps is subject to locale settings for the week day while parsing only accepts english week day names. In some cases systemd will display a relative timestamp (relative to the current time, or the time of invocation of the command) instead or in addition to an absolute timestamp as described above. A relative timestamp is formatted as follows: 2 months 5 days ago Note that any relative timestamp will also parse correctly where a timestamp is expected. (see above) Calendar events may be used to refer to one or more points in time in a single expression. They form a superset of the absolute timestamps explained above: Thu,Fri 2012-*-1,5 11:12:13 The above refers to 11:12:13 of the first or fifth day of any month of the year 2012, given that it is a thursday or friday. The weekday specification is optional. If specified it should consist of one or more english language week day names, either in the abbreviated (Wed) or non-abbreviated (Wednesday) form (case does not matter), separated by commas. Specifying two week days separated by "-" refers to a range of continuous week days. "," and "-" may be combined freely. In the date and time specifications any component may be specified as "*" in which case any value will match. Alternatively, each component can be specified as list of values separated by commas. Values may also be suffixed with "/" and a repetition value, which indicates that the value and all values plus multiples of the repetition value are matched. Either time or date specification may be omitted, in which case the current day and 00:00:00 is implied, respectively. If the second component is not specified ":00" is assumed. Timezone names may not be specified. The special expressions hourly, daily, monthly and weekly may be used as calendar events which refer to *-*-* *:00:00, *-*-* 00:00:00, *-*-01 00:00:00 and Mon *-*-* 00:00:00, respectively. Examples for valid timestamps and their normalized form: Sat,Thu,Mon-Wed,Sat-Sun → Mon-Thu,Sat,Sun *-*-* 00:00:00 Mon,Sun 12-*-* 2,1:23 → Mon,Sun 2012-*-* 01,02:23:00 Wed *-1 → Wed *-*-01 00:00:00 Wed-Wed,Wed *-1 → Wed *-*-01 00:00:00 Wed, 17:48 → Wed *-*-* 17:48:00 Wed-Sat,Tue 12-10-15 1:2:3 → Tue-Sat 2012-10-15 01:02:03 *-*-7 0:0:0 → *-*-07 00:00:00 10-15 → *-10-15 00:00:00 monday *-12-* 17:00 → Mon *-12-* 17:00:00 Mon,Fri *-*-3,1,2 *:30:45 → Mon,Fri *-*-01,02,03 *:30:45 12,14,13,12:20,10,30 → *-*-* 12,13,14:10,20,30:00 mon,fri *-1/2-1,3 *:30:45 → Mon,Fri *-01/2-01,03 *:30:45 03-05 08:05:40 → *-03-05 08:05:40 08:05:40 → *-*-* 08:05:40 05:40 → *-*-* 05:40:00 Sat,Sun 12-05 08:05:40 → Sat,Sun *-12-05 08:05:40 Sat,Sun 08:05:40 → Sat,Sun *-*-* 08:05:40 2003-03-05 05:40 → 2003-03-05 05:40:00 2003-03-05 → 2003-03-05 00:00:00 03-05 → *-03-05 00:00:00 hourly → *-*-* *:00:00 daily → *-*-* 00:00:00 monthly → *-*-01 00:00:00 weekly → Mon *-*-* 00:00:00 *:2/3 → *-*-* *:02/3:00 Calendar events are used by timer units, see systemd.timer5 for details. systemd1, journalctl1, systemd.timer5, systemd.unit5, systemd.directives7