Provided by: systemd_251.4-1ubuntu7_amd64 bug


       systemd.time - Time and date specifications


       In systemd, timestamps, time spans, and calendar events are displayed and may be specified
       in closely related syntaxes.


       Time spans refer to time durations. On display, systemd will present time spans as a
       space-separated series of time values each suffixed by a time unit. Example:

           2h 30min

       All specified time values are meant to be added up. The above hence refers to 150 minutes.
       Display is locale-independent, only English names for the time units are used.


       When parsing, systemd will accept the same time span syntax. Separating spaces may be
       omitted. The following time units are understood:

       •   usec, us, µs

       •   msec, ms

       •   seconds, second, sec, s

       •   minutes, minute, min, m

       •   hours, hour, hr, h

       •   days, day, d

       •   weeks, week, w

       •   months, month, M (defined as 30.44 days)

       •   years, year, y (defined as 365.25 days)

       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 time span permits this. Parsing is generally locale-independent, non-English names for
       the time units are not accepted.

       Examples for valid time span specifications:

           2 h
           1y 12month
           300ms20s 5day

       One can use the timespan command of systemd-analyze(1) to normalise a textual time span
       for testing and validation purposes.

       Internally, systemd generally operates with microsecond time granularity, while the
       default time unit in user-configurable time spans is usually seconds (see above). This
       disparity becomes visible when comparing the same settings in the (high-level) unit file
       syntax with the matching (more low-level) D-Bus properties (which are what systemctl(1)'s
       show command displays). The former typically are suffixed with "...Sec" to indicate the
       default unit of seconds, the latter are typically suffixed with "...USec" to indicate the
       underlying low-level time unit, even if they both encapsulate the very same settings.


       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 weekday is printed in the abbreviated English language form. The formatting is

       In some cases timestamps are shown in the UTC timezone instead of the local timezone,
       which is indicated via the "UTC" timezone specifier in the output.

       In some cases timestamps are shown with microsecond granularity. In this case the
       sub-second remainder is separated by a full stop from the seconds component.


       When parsing, systemd will accept a similar syntax, but expects no timezone specification,
       unless it is given as the literal string "UTC" (for the UTC timezone), or is specified to
       be the locally configured timezone, or the timezone name in the IANA timezone database
       format. The complete list of timezones supported on your system can be obtained using the
       "timedatectl list-timezones" (see timedatectl(1)). Using IANA format is recommended over
       local timezone names, as less prone to errors (e.g. with local timezone it's possible to
       specify daylight saving time in winter, even though that is not correct). The weekday
       specification is optional, but when the weekday is specified, it must either be in the
       abbreviated ("Wed") or non-abbreviated ("Wednesday") English language form (case does not
       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, respectively, 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 weekday is specified and the date does not 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", and "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 time span (see
       above) that is prefixed with "+" is evaluated to the current time plus the specified time
       span. Correspondingly, a time span that is prefixed with "-" is evaluated to the current
       time minus the specified time span. Instead of prefixing the time span with "+" or "-", it
       may also be suffixed with a space and the word "left" or "ago".

       Finally, a timespan prefixed with "@" is evaluated relative to the UNIX time epoch 1st
       Jan, 1970, 00:00.

       Examples for valid timestamps and their normalized form (assuming the current time was
       2012-11-23 18:15:22 and the timezone was UTC+8, for example "TZ=:Asia/Shanghai"):

             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 11:12:13 UTC → Fri 2012-11-23 19:12:13
                          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
                           today UTC → Fri 2012-11-23 16:00:00
                           yesterday → Fri 2012-11-22 00:00:00
                            tomorrow → Fri 2012-11-24 00:00:00
           tomorrow Pacific/Auckland → Thu 2012-11-23 19:00:00
                            +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
                         @1395716396 → Tue 2014-03-25 03:59:56

       Note that timestamps displayed by remote systems with a non-matching timezone are usually
       not parsable locally, as the timezone component is not understood (unless it happens to be

       Timestamps may also be specified with microsecond granularity. The sub-second remainder is
       expected separated by a full stop from the seconds component. Example:

           2014-03-25 03:59:56.654563

       In some cases, systemd will display a relative timestamp (relative to the current time, or
       the time of invocation of the command) instead of or in addition to an absolute timestamp
       as described above. A relative timestamp is formatted as follows:

           2 months 5 days ago

       Note that a relative timestamp is also accepted where a timestamp is expected (see above).

       Use the timestamp command of systemd-analyze(1) to validate and normalize timestamps for
       testing purposes.


       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, but
       only if that day is a Thursday or Friday.

       The weekday specification is optional. If specified, it should consist of one or more
       English language weekday names, either in the abbreviated (Wed) or non-abbreviated
       (Wednesday) form (case does not matter), separated by commas. Specifying two weekdays
       separated by ".."  refers to a range of continuous weekdays.  "," 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 a list of values
       separated by commas. Values may be suffixed with "/" and a repetition value, which
       indicates that the value itself and the value plus all multiples of the repetition value
       are matched. Two values separated by ".."  may be used to indicate a range of values;
       ranges may also be followed with "/" and a repetition value, in which case the expression
       matches all times starting with the start value, and continuing with all multiples of the
       repetition value relative to the start value, ending at the end value the latest.

       A date specification may use "~" to indicate the last day(s) in a month. For example,
       "*-02~03" means "the third last day in February," and "Mon *-05~07/1" means "the last
       Monday in May."

       The seconds component may contain decimal fractions both in the value and the repetition.
       All fractions are rounded to 6 decimal places.

       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

       Timezone can be specified as the literal string "UTC", or the local timezone, similar to
       the supported syntax of timestamps (see above), or the timezone in the IANA timezone
       database format (also see above).

       The following special expressions may be used as shorthands for longer normalized forms:

               minutely → *-*-* *:*:00
                 hourly → *-*-* *:00:00
                  daily → *-*-* 00:00:00
                monthly → *-*-01 00:00:00
                 weekly → Mon *-*-* 00:00:00
                 yearly → *-01-01 00:00:00
              quarterly → *-01,04,07,10-01 00:00:00
           semiannually → *-01,07-01 00:00:00

       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
                       12..14:10,20,30 → *-*-* 12..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
            05:40:23.4200004/3.1700005 → *-*-* 05:40:23.420000/3.170001
                        2003-02..04-05 → 2003-02..04-05 00:00:00
                  2003-03-05 05:40 UTC → 2003-03-05 05:40:00 UTC
                            2003-03-05 → 2003-03-05 00:00:00
                                 03-05 → *-03-05 00:00:00
                                hourly → *-*-* *:00:00
                                 daily → *-*-* 00:00:00
                             daily UTC → *-*-* 00:00:00 UTC
                               monthly → *-*-01 00:00:00
                                weekly → Mon *-*-* 00:00:00
               weekly Pacific/Auckland → Mon *-*-* 00:00:00 Pacific/Auckland
                                yearly → *-01-01 00:00:00
                              annually → *-01-01 00:00:00
                                 *:2/3 → *-*-* *:02/3:00

       Calendar events are used by timer units, see systemd.timer(5) for details.

       Use the calendar command of systemd-analyze(1) to validate and normalize calendar time
       specifications for testing purposes. The tool also calculates when a specified calendar
       event would occur next.


       systemd(1), journalctl(1), systemd.timer(5), systemd.unit(5), systemd.directives(7),