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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | |
5 | <!-- | |
572eb058 | 6 | SPDX-License-Identifier: LGPL-2.1+ |
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7 | --> |
8 | ||
9 | <refentry id="systemd.time"> | |
10 | ||
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11 | <refentryinfo> |
12 | <title>systemd.time</title> | |
13 | <productname>systemd</productname> | |
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14 | </refentryinfo> |
15 | ||
16 | <refmeta> | |
17 | <refentrytitle>systemd.time</refentrytitle> | |
18 | <manvolnum>7</manvolnum> | |
19 | </refmeta> | |
20 | ||
21 | <refnamediv> | |
22 | <refname>systemd.time</refname> | |
23 | <refpurpose>Time and date specifications</refpurpose> | |
24 | </refnamediv> | |
25 | ||
26 | <refsect1> | |
27 | <title>Description</title> | |
28 | ||
29 | <para>In systemd, timestamps, time spans, and calendar events are | |
30 | displayed and may be specified in closely related syntaxes.</para> | |
31 | </refsect1> | |
32 | ||
33 | <refsect1> | |
34 | <title>Displaying Time Spans</title> | |
35 | ||
21b3a0fc LP |
36 | <para>Time spans refer to time durations. On display, systemd will present time spans as a space-separated series |
37 | of time values each suffixed by a time unit. Example:</para> | |
798d3a52 ZJS |
38 | |
39 | <programlisting>2h 30min</programlisting> | |
40 | ||
21b3a0fc LP |
41 | <para>All specified time values are meant to be added up. The above hence refers to 150 minutes. Display is |
42 | locale-independent, only English names for the time units are used.</para> | |
798d3a52 ZJS |
43 | </refsect1> |
44 | ||
45 | <refsect1> | |
46 | <title>Parsing Time Spans</title> | |
47 | ||
48 | <para>When parsing, systemd will accept the same time span syntax. | |
49 | Separating spaces may be omitted. The following time units are | |
50 | understood:</para> | |
51 | ||
52 | <itemizedlist> | |
53 | <listitem><para>usec, us</para></listitem> | |
54 | <listitem><para>msec, ms</para></listitem> | |
55 | <listitem><para>seconds, second, sec, s</para></listitem> | |
56 | <listitem><para>minutes, minute, min, m</para></listitem> | |
57 | <listitem><para>hours, hour, hr, h</para></listitem> | |
58 | <listitem><para>days, day, d</para></listitem> | |
59 | <listitem><para>weeks, week, w</para></listitem> | |
7236f0c6 | 60 | <listitem><para>months, month, M (defined as 30.44 days)</para></listitem> |
21b3a0fc | 61 | <listitem><para>years, year, y (defined as 365.25 days)</para></listitem> |
798d3a52 ZJS |
62 | </itemizedlist> |
63 | ||
21b3a0fc LP |
64 | <para>If no time unit is specified, generally seconds are assumed, but some exceptions exist and are marked as |
65 | such. In a few cases <literal>ns</literal>, <literal>nsec</literal> is accepted too, where the granularity of the | |
66 | time span permits this. Parsing is generally locale-independent, non-English names for the time units are not | |
67 | accepted.</para> | |
798d3a52 ZJS |
68 | |
69 | <para>Examples for valid time span specifications:</para> | |
70 | ||
71 | <programlisting>2 h | |
7a529f63 LP |
72 | 2hours |
73 | 48hr | |
74 | 1y 12month | |
75 | 55s500ms | |
76 | 300ms20s 5day</programlisting> | |
798d3a52 ZJS |
77 | </refsect1> |
78 | ||
79 | <refsect1> | |
80 | <title>Displaying Timestamps</title> | |
81 | ||
82 | <para>Timestamps refer to specific, unique points in time. On | |
83 | display, systemd will format these in the local timezone as | |
84 | follows:</para> | |
85 | ||
86 | <programlisting>Fri 2012-11-23 23:02:15 CET</programlisting> | |
87 | ||
21b3a0fc LP |
88 | <para>The weekday is printed in the abbreviated English language form. The formatting is locale-independent.</para> |
89 | ||
90 | <para>In some cases timestamps are shown in the UTC timezone instead of the local timezone, which is indicated via | |
91 | the <literal>UTC</literal> timezone specifier in the output.</para> | |
92 | ||
93 | <para>In some cases timestamps are shown with microsecond granularity. In this case the sub-second remainder is | |
94 | separated by a full stop from the seconds component.</para> | |
798d3a52 ZJS |
95 | </refsect1> |
96 | ||
97 | <refsect1> | |
98 | <title>Parsing Timestamps</title> | |
99 | ||
21b3a0fc | 100 | <para>When parsing, systemd will accept a similar syntax, but expects no timezone specification, unless it is given |
54d3be97 IK |
101 | as the literal string <literal>UTC</literal> (for the UTC timezone), or is specified to be the locally configured |
102 | timezone, or the timezone name in the IANA timezone database format. The complete list of timezones | |
103 | supported on your system can be obtained using the <literal>timedatectl list-timezones</literal> | |
104 | (see <citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>). | |
105 | Using IANA format is recommended over local timezone names, as less prone to errors (eg: with local timezone it's possible to | |
106 | specify daylight saving time in winter, while it's incorrect). The weekday specification is optional, but when | |
21b3a0fc LP |
107 | the weekday is specified, it must either be in the abbreviated (<literal>Wed</literal>) or non-abbreviated |
108 | (<literal>Wednesday</literal>) English language form (case does not matter), and is not subject to the locale | |
109 | choice of the user. Either the date, or the time part may be omitted, in which case the current date or 00:00:00, | |
110 | respectively, is assumed. The seconds component of the time may also be omitted, in which case ":00" is | |
111 | assumed. Year numbers may be specified in full or may be abbreviated (omitting the century).</para> | |
112 | ||
113 | <para>A timestamp is considered invalid if a weekday is specified and the date does not match the specified day of | |
114 | the week.</para> | |
798d3a52 ZJS |
115 | |
116 | <para>When parsing, systemd will also accept a few special | |
117 | placeholders instead of timestamps: <literal>now</literal> may be | |
118 | used to refer to the current time (or of the invocation of the | |
119 | command that is currently executed). <literal>today</literal>, | |
a8eaaee7 | 120 | <literal>yesterday</literal>, and <literal>tomorrow</literal> refer to |
b938cb90 | 121 | 00:00:00 of the current day, the day before, or the next day, |
798d3a52 ZJS |
122 | respectively.</para> |
123 | ||
124 | <para>When parsing, systemd will also accept relative time | |
125 | specifications. A time span (see above) that is prefixed with | |
126 | <literal>+</literal> is evaluated to the current time plus the | |
127 | specified time span. Correspondingly, a time span that is prefixed | |
128 | with <literal>-</literal> is evaluated to the current time minus | |
129 | the specified time span. Instead of prefixing the time span with | |
130 | <literal>+</literal> or <literal>-</literal>, it may also be | |
131 | suffixed with a space and the word <literal>left</literal> or | |
132 | <literal>ago</literal>.</para> | |
133 | ||
134 | <para>Finally, a timespan prefixed with <literal>@</literal> is | |
135 | evaluated relative to the UNIX time epoch 1st Jan, 1970, | |
136 | 00:00.</para> | |
137 | ||
138 | <para>Examples for valid timestamps and their normalized form | |
d08a6b02 HV |
139 | (assuming the current time was 2012-11-23 18:15:22 and the timezone |
140 | was UTC+8, for example TZ=Asia/Shanghai):</para> | |
798d3a52 | 141 | |
54d3be97 IK |
142 | <programlisting> Fri 2012-11-23 11:12:13 → Fri 2012-11-23 11:12:13 |
143 | 2012-11-23 11:12:13 → Fri 2012-11-23 11:12:13 | |
144 | 2012-11-23 11:12:13 UTC → Fri 2012-11-23 19:12:13 | |
145 | 2012-11-23 → Fri 2012-11-23 00:00:00 | |
146 | 12-11-23 → Fri 2012-11-23 00:00:00 | |
147 | 11:12:13 → Fri 2012-11-23 11:12:13 | |
148 | 11:12 → Fri 2012-11-23 11:12:00 | |
149 | now → Fri 2012-11-23 18:15:22 | |
150 | today → Fri 2012-11-23 00:00:00 | |
151 | today UTC → Fri 2012-11-23 16:00:00 | |
152 | yesterday → Fri 2012-11-22 00:00:00 | |
153 | tomorrow → Fri 2012-11-24 00:00:00 | |
154 | tomorrow Pacific/Auckland → Thu 2012-11-23 19:00:00 | |
155 | +3h30min → Fri 2012-11-23 21:45:22 | |
156 | -5s → Fri 2012-11-23 18:15:17 | |
157 | 11min ago → Fri 2012-11-23 18:04:22 | |
158 | @1395716396 → Tue 2014-03-25 03:59:56</programlisting> | |
798d3a52 | 159 | |
21b3a0fc LP |
160 | <para>Note that timestamps displayed by remote systems with a non-matching timezone are usually not parsable |
161 | locally, as the timezone component is not understood (unless it happens to be <literal>UTC</literal>).</para> | |
798d3a52 | 162 | |
21b3a0fc LP |
163 | <para>Timestamps may also be specified with microsecond granularity. The sub-second remainder is expected separated |
164 | by a full stop from the seconds component. Example:</para> | |
165 | ||
166 | <programlisting>2014-03-25 03:59:56.654563</programlisting> | |
167 | ||
168 | <para>In some cases, systemd will display a relative timestamp (relative to the current time, or the time of | |
169 | invocation of the command) instead of or in addition to an absolute timestamp as described above. A relative | |
170 | timestamp is formatted as follows:</para> | |
798d3a52 | 171 | |
21b3a0fc | 172 | <programlisting>2 months 5 days ago</programlisting> |
798d3a52 | 173 | |
21b3a0fc | 174 | <para>Note that a relative timestamp is also accepted where a timestamp is expected (see above).</para> |
798d3a52 ZJS |
175 | </refsect1> |
176 | ||
177 | <refsect1> | |
178 | <title>Calendar Events</title> | |
179 | ||
180 | <para>Calendar events may be used to refer to one or more points | |
181 | in time in a single expression. They form a superset of the | |
182 | absolute timestamps explained above:</para> | |
183 | ||
184 | <programlisting>Thu,Fri 2012-*-1,5 11:12:13</programlisting> | |
185 | ||
186 | <para>The above refers to 11:12:13 of the first or fifth day of | |
187 | any month of the year 2012, but only if that day is a Thursday or | |
188 | Friday.</para> | |
189 | ||
190 | <para>The weekday specification is optional. If specified, it | |
191 | should consist of one or more English language weekday names, | |
192 | either in the abbreviated (Wed) or non-abbreviated (Wednesday) | |
193 | form (case does not matter), separated by commas. Specifying two | |
e638d050 DC |
194 | weekdays separated by <literal>..</literal> refers to a range of |
195 | continuous weekdays. <literal>,</literal> and <literal>..</literal> | |
798d3a52 ZJS |
196 | may be combined freely.</para> |
197 | ||
198 | <para>In the date and time specifications, any component may be | |
199 | specified as <literal>*</literal> in which case any value will | |
200 | match. Alternatively, each component can be specified as a list of | |
a2eb5ea7 | 201 | values separated by commas. Values may be suffixed with |
798d3a52 | 202 | <literal>/</literal> and a repetition value, which indicates that |
d6cdc4cd | 203 | the value itself and the value plus all multiples of the repetition value |
a2eb5ea7 DC |
204 | are matched. Two values separated by <literal>..</literal> may be used |
205 | to indicate a range of values; ranges may also be followed with | |
206 | <literal>/</literal> and a repetition value.</para> | |
798d3a52 | 207 | |
8ea80351 DC |
208 | <para>A date specification may use <literal>~</literal> to indicate the |
209 | last day(s) in a month. For example, <literal>*-02~03</literal> means | |
210 | "the third last day in February," and <literal>Mon *-05~07/1</literal> | |
211 | means "the last Monday in May."</para> | |
212 | ||
ab15dfb7 HV |
213 | <para>The seconds component may contain decimal fractions both in |
214 | the value and the repetition. All fractions are rounded to 6 | |
215 | decimal places.</para> | |
216 | ||
798d3a52 ZJS |
217 | <para>Either time or date specification may be omitted, in which |
218 | case the current day and 00:00:00 is implied, respectively. If the | |
219 | second component is not specified, <literal>:00</literal> is | |
220 | assumed.</para> | |
221 | ||
54d3be97 IK |
222 | <para>Timezone can be specified as the literal string <literal>UTC</literal>, or |
223 | the local timezone, similar to the supported syntax of timestamps (see above), or the timezone | |
224 | in the IANA timezone database format (also see above).</para> | |
798d3a52 | 225 | |
6d892bd1 MS |
226 | <para>The following special expressions may be used as shorthands for longer normalized forms:</para> |
227 | ||
228 | <programlisting> minutely → *-*-* *:*:00 | |
229 | hourly → *-*-* *:00:00 | |
230 | daily → *-*-* 00:00:00 | |
231 | monthly → *-*-01 00:00:00 | |
232 | weekly → Mon *-*-* 00:00:00 | |
233 | yearly → *-01-01 00:00:00 | |
234 | quarterly → *-01,04,07,10-01 00:00:00 | |
235 | semiannually → *-01,07-01 00:00:00 | |
236 | </programlisting> | |
798d3a52 ZJS |
237 | |
238 | <para>Examples for valid timestamps and their | |
239 | normalized form:</para> | |
7a529f63 | 240 | |
21b3a0fc LP |
241 | <programlisting> Sat,Thu,Mon..Wed,Sat..Sun → Mon..Thu,Sat,Sun *-*-* 00:00:00 |
242 | Mon,Sun 12-*-* 2,1:23 → Mon,Sun 2012-*-* 01,02:23:00 | |
243 | Wed *-1 → Wed *-*-01 00:00:00 | |
e638d050 | 244 | Wed..Wed,Wed *-1 → Wed *-*-01 00:00:00 |
21b3a0fc | 245 | Wed, 17:48 → Wed *-*-* 17:48:00 |
e638d050 | 246 | Wed..Sat,Tue 12-10-15 1:2:3 → Tue..Sat 2012-10-15 01:02:03 |
21b3a0fc LP |
247 | *-*-7 0:0:0 → *-*-07 00:00:00 |
248 | 10-15 → *-10-15 00:00:00 | |
249 | monday *-12-* 17:00 → Mon *-12-* 17:00:00 | |
250 | Mon,Fri *-*-3,1,2 *:30:45 → Mon,Fri *-*-01,02,03 *:30:45 | |
251 | 12,14,13,12:20,10,30 → *-*-* 12,13,14:10,20,30:00 | |
9904dc00 | 252 | 12..14:10,20,30 → *-*-* 12..14:10,20,30:00 |
21b3a0fc LP |
253 | mon,fri *-1/2-1,3 *:30:45 → Mon,Fri *-01/2-01,03 *:30:45 |
254 | 03-05 08:05:40 → *-03-05 08:05:40 | |
255 | 08:05:40 → *-*-* 08:05:40 | |
256 | 05:40 → *-*-* 05:40:00 | |
257 | Sat,Sun 12-05 08:05:40 → Sat,Sun *-12-05 08:05:40 | |
258 | Sat,Sun 08:05:40 → Sat,Sun *-*-* 08:05:40 | |
259 | 2003-03-05 05:40 → 2003-03-05 05:40:00 | |
a2eb5ea7 | 260 | 05:40:23.4200004/3.1700005 → *-*-* 05:40:23.420000/3.170001 |
9904dc00 | 261 | 2003-02..04-05 → 2003-02..04-05 00:00:00 |
21b3a0fc LP |
262 | 2003-03-05 05:40 UTC → 2003-03-05 05:40:00 UTC |
263 | 2003-03-05 → 2003-03-05 00:00:00 | |
264 | 03-05 → *-03-05 00:00:00 | |
265 | hourly → *-*-* *:00:00 | |
266 | daily → *-*-* 00:00:00 | |
267 | daily UTC → *-*-* 00:00:00 UTC | |
268 | monthly → *-*-01 00:00:00 | |
269 | weekly → Mon *-*-* 00:00:00 | |
54d3be97 | 270 | weekly Pacific/Auckland → Mon *-*-* 00:00:00 Pacific/Auckland |
21b3a0fc LP |
271 | yearly → *-01-01 00:00:00 |
272 | annually → *-01-01 00:00:00 | |
273 | *:2/3 → *-*-* *:02/3:00</programlisting> | |
798d3a52 ZJS |
274 | |
275 | <para>Calendar events are used by timer units, see | |
276 | <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
277 | for details.</para> | |
278 | ||
6d86f4bd LP |
279 | <para>Use the <command>calendar</command> command of |
280 | <citerefentry><refentrytitle>systemd-analyze</refentrytitle><manvolnum>1</manvolnum></citerefentry> to validate | |
281 | and normalize calendar time specifications for testing purposes. The tool also calculates when a specified | |
282 | calendar event would elapse next.</para> | |
798d3a52 ZJS |
283 | </refsect1> |
284 | ||
285 | <refsect1> | |
286 | <title>See Also</title> | |
287 | <para> | |
288 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
289 | <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
290 | <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
291 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
6d86f4bd LP |
292 | <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
293 | <citerefentry><refentrytitle>systemd-analyze</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
798d3a52 ZJS |
294 | </para> |
295 | </refsect1> | |
7a529f63 LP |
296 | |
297 | </refentry> |