# systemd.time

## 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 some
           fields can be omitted, and the space between the date and time can
           be replaced with a "T" (à la the **RFC 3339******[1] profile of ISO 8601);
           thus, in CET, the following are all identical: "Fri 2012-11-23
           23:02:15 CET", "Fri 2012-11-23T23:02:15", "2012-11-23T23:02:15
           CET", "2012-11-23 23:02:15".
    
           The timezone defaults to the current timezone if not specified
           explicitly. It may be given after a space, like above, in which
           case it can be: "UTC", an entry in the installed IANA timezone
           database (e.g.  "CET", "Asia/Tokyo", where the complete list can
           be obtained with**timedatectl list-timezones**(see timedatectl(1))),
           or "± _05_ ", "± _0530_ ", "± _05_ :_30_ ", "Z".
    
           It may also be affixed directly to the timestamp, in which case it
           must correspond to one of the formats defined in the **RFC 3339******[1]
           profile of ISO 8601: "± _05_ :_30_ " or "Z". Thus, the following are also
           identical to the above: "2012-11-23T23:02:15+01:00", "2012-11-23
           22:02:15Z".
    
           A timestamp can start with a field containing a weekday, which can
           be in an abbreviated ("Wed") or non-abbreviated ("Wednesday")
           English language form (case does not matter), regardless of the
           locale. However, if a weekday _is_ specified and does not match the
           date, the timestamp is rejected.
    
           If the date is omitted, it defaults to today. If the time is
           omitted, it defaults to 00:00:00. Fractional seconds can be
           specified down to 1µs precision. The seconds field can also be
           omitted, defaulting to 0.
    
           There are special tokens that can be used in place 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.
    
           Relative times are also accepted: a time span (see above) 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, an integer prefixed with "@" is evaluated relative to the
           UNIX epoch – 1970-01-01 00:00:00 UTC.
    
           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
                    2012-11-23T11:12:13Z → Fri 2012-11-23 19:12:13
                  2012-11-23T11:12+02:00 → Fri 2012-11-23 17:12:00
                              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 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
           00:00:00 and *-*-* is implied, respectively. If the seconds
           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.
    


## NOTES



            1. RFC 3339
               https://tools.ietf.org/html/rfc3339
    


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