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<refentry id="systemd.time">

<refentryinfo>

<title>systemd.time</title>

<productname>systemd</productname>

<authorgroup>

<author>

<contrib>Developer</contrib>

<firstname>Lennart</firstname>

<surname>Poettering</surname>

<email>lennart@poettering.net</email>

</author>

</authorgroup>

</refentryinfo>

<refmeta>

<refentrytitle>systemd.time</refentrytitle>

<manvolnum>7</manvolnum>

</refmeta>

<refnamediv>

<refname>systemd.time</refname>

<refpurpose>Time and date specifications</refpurpose>

</refnamediv>

<refsect1>

<title>Description</title>

<para>In systemd timestamps, timespans, and calendar

events are displayed and may be specified in closely

related syntaxes.</para>

</refsect1>

<refsect1>

<title>Displaying Timespans</title>

<para>Timespans refer to time durations. On display

systemd will present timespans as a space separated

series of time values each suffixed by a time

unit.</para>

<programlisting>2h 30min</programlisting>

<para>All specified time values are meant to be added

up. The above hence refers to 150 minutes.</para>

</refsect1>

<refsect1>

<title>Parsing Timespans</title>

<para>When parsing systemd will accept the same

timespan syntax. Separating spaces may be omitted. The

following time units are understood:</para>

<itemizedlist>

<listitem><para>usec, us</para></listitem>

<listitem><para>msec, ms</para></listitem>

<listitem><para>seconds, second, sec, s</para></listitem>

<listitem><para>minutes, minute, min, m</para></listitem>

<listitem><para>hours, hour, hr, h</para></listitem>

<listitem><para>days, day, d</para></listitem>

<listitem><para>weeks, week, w</para></listitem>

<listitem><para>months, month</para></listitem>

<listitem><para>years, year, y</para></listitem>

</itemizedlist>

<para>If no time unit is specified, generally seconds

are assumed, but some exceptions exist and are marked

as such. In a few cases <literal>ns</literal>,

<literal>nsec</literal> is accepted too, where the

granularity of the timespan allows for this.</para>

<para>Examples for valid timespan specifications:</para>

<programlisting>2 h

2hours

48hr

1y 12month

55s500ms

300ms20s 5day</programlisting>

</refsect1>

<refsect1>

<title>Displaying Timestamps</title>

<para>Timestamps refer to specific, unique points in

time. On display systemd will format these in the

local timezone as follows:</para>

<programlisting>Fri 2012-11-23 23:02:15 CET</programlisting>

<para>The week day is printed according to the locale

choice of the user.</para>

</refsect1>

<refsect1>

<title>Parsing Timestamps</title>

<para>When parsing systemd will accept a similar

timestamp syntax, but excluding any timezone

specification (this limitation might be removed

eventually). The week day specification is optional,

but when the week day is specified it must either be

in the abbreviated (<literal>Wed</literal>) or

non-abbreviated (<literal>Wednesday</literal>) english

language form (case doesn't 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, resp., 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).</para>

<para>A timestamp is considered invalid if a week day

is specified and the date does not actually match the

specified day of the week.</para>

<para>When parsing systemd will also accept a few

special placeholders instead of timestamps:

<literal>now</literal> may be used to refer to the

current time (or of the invocation of the command

that is currently executed). <literal>today</literal>,

<literal>yesterday</literal>,

<literal>tomorrow</literal> refer to 00:00:00 of the

current day, the day before or the next day,

respectively.</para>

<para>When parsing systemd will also accept relative

time specifications. A timespan (see above) that is

prefixed with <literal>+</literal> is evaluated to the

current time plus the specified

timespan. Correspondingly a timespan that is prefix

with <literal>-</literal> is evaluated to the current

time minus the specified timespan. Instead of

prefixing the timespan with <literal>-</literal> it

may also be suffixed with a space and the word

<literal>ago</literal>.</para>

<para>Examples for valid timestamps and their

normalized form (assuming the current time was

2012-11-23 18:15:22):</para>

<programlisting>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 → 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

yesterday → Fri 2012-11-22 00:00:00

tomorrow → Fri 2012-11-24 00:00:00

+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</programlisting>

<para>Note that timestamps printed by systemd will not

be parsed correctly by systemd, as the timezone

specification is not accepted, and printing timestamps

is subject to locale settings for the week day while

parsing only accepts english week day names.</para>

<para>In some cases systemd will display a relative

timestamp (relative to the current time, or the time

of invocation of the command) instead or in addition

to an absolute timestamp as described above. A

relative timestamp is formatted as follows:</para>

<para>2 months 5 days ago</para>

<para>Note that any relative timestamp will also parse

correctly where a timestamp is expected. (see above)</para>

</refsect1>

<refsect1>

<title>Calendar Events</title>

<para>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:</para>

<programlisting>Thu,Fri 2012-*-1,5 11:12:13</programlisting>

<para>The above refers to 11:12:13 of the first or

fifth day of any month of the year 2012, given that it

is a thursday or friday.</para>

<para>The weekday specification is optional. If

specified it should consist of one or more english

language week day names, either in the abbreviated

(Wed) or non-abbreviated (Wednesday) form (case does

not matter), separated by colons. Specifying two week

days separated by "-" refers to a range of continuous

week days. "," and "-" may be combined freely.</para>

<para>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 list of values separated by

colons. Values may also be suffixed with "/" and a

repetition value, which indicates that the value and

all values plus multiples of the repetition value are

matched.</para>

<para>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.</para>

<para>Timezone names may not be specified.</para>

<para>The special expressions

<literal>hourly</literal>, <literal>daily</literal>,

<literal>monthly</literal> and <literal>weekly</literal>

may be used as calendar events which refer to

<literal>*-*-* *:00:00</literal>, <literal>*-*-*

00:00:00</literal>, <literal>*-*-01 00:00:00</literal> and

<literal>Mon *-*-* 00:00:00</literal>,

respectively.</para>

<para>Examples for valid timestamps and their

normalized form:</para>

<programlisting> 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

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

2003-03-05 → 2003-03-05 00:00:00

03-05 → *-03-05 00:00:00

hourly → *-*-* *:00:00

daily → *-*-* 00:00:00

monthly → *-*-01 00:00:00

weekly → Mon *-*-* 00:00:00

*:2/3 → *-*-* *:02/3:00</programlisting>

<para>Calendar events are used by timer units, see

<citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>

for details.</para>

</refsect1>

<refsect1>

<title>See Also</title>

<para>

<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>