характеристики времени и даты (Time and date specifications)
Имя (Name)
systemd.time - Time and date specifications
Описание (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.
Смотри также (See also)
systemd(1), journalctl(1), systemd.timer(5), systemd.unit(5),
systemd.directives(7), systemd-analyze(1)
