systemd.time

SYSTEMD.TIME(7)                   systemd.time                   SYSTEMD.TIME(7)



NAME
       systemd.time - Time and date specifications

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

DISPLAYING TIME SPANS
       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.

PARSING TIME SPANS
       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
           2hours
           48hr
           1y 12month
           55s500ms
           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.

DISPLAYING TIMESTAMPS
       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 locale-independent.

       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.

PARSING TIMESTAMPS
       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 "UTC").

       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
       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 assumed.

       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.

SEE ALSO
       systemd(1), journalctl(1), systemd.timer(5), systemd.unit(5),
       systemd.directives(7), systemd-analyze(1)



systemd 247                                                      SYSTEMD.TIME(7)