systemd.time(7) — Linux manual page

NAME | DESCRIPTION | DISPLAYING TIME SPANS | PARSING TIME SPANS | DISPLAYING TIMESTAMPS | PARSING TIMESTAMPS | CALENDAR EVENTS | SEE ALSO | COLOPHON

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

NAME         top

       systemd.time - Time and date specifications

DESCRIPTION         top

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

DISPLAYING TIME SPANS         top

       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         top

       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         top

       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         top

       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         top

       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         top

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

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have
       a bug report for this manual page, see
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2020-12-18.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2020-12-18.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

systemd 247                                              SYSTEMD.TIME(7)

Pages that refer to this page: homectl(1)journalctl(1)systemd-analyze(1)systemd-mount(1)systemd.exec(5)systemd.socket(5)systemd.timer(5)systemd.unit(5)systemd.index(7)systemd.syntax(7)