Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1 | :mod:`time` --- Time access and conversions |
| 2 | =========================================== |
| 3 | |
| 4 | .. module:: time |
| 5 | :synopsis: Time access and conversions. |
| 6 | |
| 7 | |
| 8 | This module provides various time-related functions. For related |
| 9 | functionality, see also the :mod:`datetime` and :mod:`calendar` modules. |
| 10 | |
| 11 | Although this module is always available, |
| 12 | not all functions are available on all platforms. Most of the functions |
| 13 | defined in this module call platform C library functions with the same name. It |
| 14 | may sometimes be helpful to consult the platform documentation, because the |
| 15 | semantics of these functions varies among platforms. |
| 16 | |
| 17 | An explanation of some terminology and conventions is in order. |
| 18 | |
Georg Brandl | b67878a | 2010-10-15 17:01:15 +0000 | [diff] [blame] | 19 | .. index:: single: epoch |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 20 | |
| 21 | * The :dfn:`epoch` is the point where the time starts. On January 1st of that |
| 22 | year, at 0 hours, the "time since the epoch" is zero. For Unix, the epoch is |
| 23 | 1970. To find out what the epoch is, look at ``gmtime(0)``. |
| 24 | |
Georg Brandl | b67878a | 2010-10-15 17:01:15 +0000 | [diff] [blame] | 25 | .. index:: single: Year 2038 |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 26 | |
Alexander Belopolsky | c64708a | 2011-01-07 19:59:19 +0000 | [diff] [blame] | 27 | * The functions in this module may not handle dates and times before the epoch or |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 28 | far in the future. The cut-off point in the future is determined by the C |
Alexander Belopolsky | c64708a | 2011-01-07 19:59:19 +0000 | [diff] [blame] | 29 | library; for 32-bit systems, it is typically in 2038. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 30 | |
Georg Brandl | b67878a | 2010-10-15 17:01:15 +0000 | [diff] [blame] | 31 | .. index:: |
| 32 | single: Year 2000 |
| 33 | single: Y2K |
| 34 | |
| 35 | .. _time-y2kissues: |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 36 | |
Alexander Belopolsky | c64708a | 2011-01-07 19:59:19 +0000 | [diff] [blame] | 37 | * **Year 2000 (Y2K) issues**: Python depends on the platform's C library, which |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 38 | generally doesn't have year 2000 issues, since all dates and times are |
Alexander Belopolsky | c64708a | 2011-01-07 19:59:19 +0000 | [diff] [blame] | 39 | represented internally as seconds since the epoch. Function :func:`strptime` |
| 40 | can parse 2-digit years when given ``%y`` format code. When 2-digit years are |
| 41 | parsed, they are converted according to the POSIX and ISO C standards: values |
| 42 | 69--99 are mapped to 1969--1999, and values 0--68 are mapped to 2000--2068. |
| 43 | |
Georg Brandl | b67878a | 2010-10-15 17:01:15 +0000 | [diff] [blame] | 44 | .. index:: |
| 45 | single: UTC |
| 46 | single: Coordinated Universal Time |
| 47 | single: Greenwich Mean Time |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 48 | |
| 49 | * UTC is Coordinated Universal Time (formerly known as Greenwich Mean Time, or |
| 50 | GMT). The acronym UTC is not a mistake but a compromise between English and |
| 51 | French. |
| 52 | |
Georg Brandl | b67878a | 2010-10-15 17:01:15 +0000 | [diff] [blame] | 53 | .. index:: single: Daylight Saving Time |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 54 | |
| 55 | * DST is Daylight Saving Time, an adjustment of the timezone by (usually) one |
| 56 | hour during part of the year. DST rules are magic (determined by local law) and |
| 57 | can change from year to year. The C library has a table containing the local |
| 58 | rules (often it is read from a system file for flexibility) and is the only |
| 59 | source of True Wisdom in this respect. |
| 60 | |
| 61 | * The precision of the various real-time functions may be less than suggested by |
| 62 | the units in which their value or argument is expressed. E.g. on most Unix |
Georg Brandl | c575c90 | 2008-09-13 17:46:05 +0000 | [diff] [blame] | 63 | systems, the clock "ticks" only 50 or 100 times a second. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 64 | |
Petri Lehtinen | 1033b31 | 2012-05-18 21:19:17 +0300 | [diff] [blame] | 65 | * On the other hand, the precision of :func:`.time` and :func:`sleep` is better |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 66 | than their Unix equivalents: times are expressed as floating point numbers, |
Petri Lehtinen | 1033b31 | 2012-05-18 21:19:17 +0300 | [diff] [blame] | 67 | :func:`.time` returns the most accurate time available (using Unix |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 68 | :c:func:`gettimeofday` where available), and :func:`sleep` will accept a time |
| 69 | with a nonzero fraction (Unix :c:func:`select` is used to implement this, where |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 70 | available). |
| 71 | |
| 72 | * The time value as returned by :func:`gmtime`, :func:`localtime`, and |
| 73 | :func:`strptime`, and accepted by :func:`asctime`, :func:`mktime` and |
| 74 | :func:`strftime`, is a sequence of 9 integers. The return values of |
| 75 | :func:`gmtime`, :func:`localtime`, and :func:`strptime` also offer attribute |
| 76 | names for individual fields. |
| 77 | |
Georg Brandl | b67878a | 2010-10-15 17:01:15 +0000 | [diff] [blame] | 78 | See :class:`struct_time` for a description of these objects. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 79 | |
Alexander Belopolsky | c142bba | 2012-06-13 22:15:26 -0400 | [diff] [blame] | 80 | .. versionchanged:: 3.3 |
Georg Brandl | 61063cc | 2012-06-24 22:48:30 +0200 | [diff] [blame] | 81 | The :class:`struct_time` type was extended to provide the :attr:`tm_gmtoff` |
| 82 | and :attr:`tm_zone` attributes when platform supports corresponding |
| 83 | ``struct tm`` members. |
Alexander Belopolsky | c142bba | 2012-06-13 22:15:26 -0400 | [diff] [blame] | 84 | |
Benjamin Peterson | e0124bd | 2009-03-09 21:04:33 +0000 | [diff] [blame] | 85 | * Use the following functions to convert between time representations: |
| 86 | |
| 87 | +-------------------------+-------------------------+-------------------------+ |
| 88 | | From | To | Use | |
| 89 | +=========================+=========================+=========================+ |
| 90 | | seconds since the epoch | :class:`struct_time` in | :func:`gmtime` | |
| 91 | | | UTC | | |
| 92 | +-------------------------+-------------------------+-------------------------+ |
| 93 | | seconds since the epoch | :class:`struct_time` in | :func:`localtime` | |
| 94 | | | local time | | |
| 95 | +-------------------------+-------------------------+-------------------------+ |
| 96 | | :class:`struct_time` in | seconds since the epoch | :func:`calendar.timegm` | |
| 97 | | UTC | | | |
| 98 | +-------------------------+-------------------------+-------------------------+ |
| 99 | | :class:`struct_time` in | seconds since the epoch | :func:`mktime` | |
| 100 | | local time | | | |
| 101 | +-------------------------+-------------------------+-------------------------+ |
| 102 | |
| 103 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 104 | The module defines the following functions and data items: |
| 105 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 106 | .. data:: altzone |
| 107 | |
| 108 | The offset of the local DST timezone, in seconds west of UTC, if one is defined. |
| 109 | This is negative if the local DST timezone is east of UTC (as in Western Europe, |
| 110 | including the UK). Only use this if ``daylight`` is nonzero. |
| 111 | |
| 112 | |
| 113 | .. function:: asctime([t]) |
| 114 | |
| 115 | Convert a tuple or :class:`struct_time` representing a time as returned by |
Alexander Belopolsky | b9588b5 | 2011-01-04 16:34:30 +0000 | [diff] [blame] | 116 | :func:`gmtime` or :func:`localtime` to a string of the following |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 117 | form: ``'Sun Jun 20 23:21:05 1993'``. If *t* is not provided, the current time |
| 118 | as returned by :func:`localtime` is used. Locale information is not used by |
| 119 | :func:`asctime`. |
| 120 | |
| 121 | .. note:: |
| 122 | |
Georg Brandl | 538343d | 2012-02-02 22:22:19 +0100 | [diff] [blame] | 123 | Unlike the C function of the same name, :func:`asctime` does not add a |
| 124 | trailing newline. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 125 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 126 | |
Victor Stinner | 4195b5c | 2012-02-08 23:03:19 +0100 | [diff] [blame] | 127 | .. function:: clock() |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 128 | |
| 129 | .. index:: |
| 130 | single: CPU time |
| 131 | single: processor time |
| 132 | single: benchmarking |
| 133 | |
| 134 | On Unix, return the current processor time as a floating point number expressed |
| 135 | in seconds. The precision, and in fact the very definition of the meaning of |
Georg Brandl | 01546a8 | 2014-10-28 21:35:35 +0100 | [diff] [blame] | 136 | "processor time", depends on that of the C function of the same name. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 137 | |
| 138 | On Windows, this function returns wall-clock seconds elapsed since the first |
| 139 | call to this function, as a floating point number, based on the Win32 function |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 140 | :c:func:`QueryPerformanceCounter`. The resolution is typically better than one |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 141 | microsecond. |
| 142 | |
Victor Stinner | 47620a6 | 2012-04-29 02:52:39 +0200 | [diff] [blame] | 143 | .. deprecated:: 3.3 |
| 144 | The behaviour of this function depends on the platform: use |
| 145 | :func:`perf_counter` or :func:`process_time` instead, depending on your |
| 146 | requirements, to have a well defined behaviour. |
| 147 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 148 | |
Victor Stinner | 4195b5c | 2012-02-08 23:03:19 +0100 | [diff] [blame] | 149 | .. function:: clock_getres(clk_id) |
Victor Stinner | e0be423 | 2011-10-25 13:06:09 +0200 | [diff] [blame] | 150 | |
| 151 | Return the resolution (precision) of the specified clock *clk_id*. |
| 152 | |
Victor Stinner | ca6e40f | 2012-04-28 23:47:33 +0200 | [diff] [blame] | 153 | Availability: Unix. |
| 154 | |
Victor Stinner | e0be423 | 2011-10-25 13:06:09 +0200 | [diff] [blame] | 155 | .. versionadded:: 3.3 |
| 156 | |
Georg Brandl | 909f5bc | 2012-03-29 09:18:14 +0200 | [diff] [blame] | 157 | |
Victor Stinner | 4195b5c | 2012-02-08 23:03:19 +0100 | [diff] [blame] | 158 | .. function:: clock_gettime(clk_id) |
Victor Stinner | e0be423 | 2011-10-25 13:06:09 +0200 | [diff] [blame] | 159 | |
| 160 | Return the time of the specified clock *clk_id*. |
| 161 | |
Victor Stinner | ca6e40f | 2012-04-28 23:47:33 +0200 | [diff] [blame] | 162 | Availability: Unix. |
| 163 | |
Victor Stinner | e0be423 | 2011-10-25 13:06:09 +0200 | [diff] [blame] | 164 | .. versionadded:: 3.3 |
| 165 | |
Georg Brandl | 909f5bc | 2012-03-29 09:18:14 +0200 | [diff] [blame] | 166 | |
Victor Stinner | 30d7947 | 2012-04-03 00:45:07 +0200 | [diff] [blame] | 167 | .. function:: clock_settime(clk_id, time) |
| 168 | |
| 169 | Set the time of the specified clock *clk_id*. |
| 170 | |
Victor Stinner | ca6e40f | 2012-04-28 23:47:33 +0200 | [diff] [blame] | 171 | Availability: Unix. |
| 172 | |
Victor Stinner | 30d7947 | 2012-04-03 00:45:07 +0200 | [diff] [blame] | 173 | .. versionadded:: 3.3 |
| 174 | |
| 175 | |
Victor Stinner | 1470f35 | 2012-04-03 00:31:17 +0200 | [diff] [blame] | 176 | .. data:: CLOCK_HIGHRES |
| 177 | |
| 178 | The Solaris OS has a CLOCK_HIGHRES timer that attempts to use an optimal |
Georg Brandl | 514880c | 2012-04-30 12:50:30 +0200 | [diff] [blame] | 179 | hardware source, and may give close to nanosecond resolution. CLOCK_HIGHRES |
Victor Stinner | 1470f35 | 2012-04-03 00:31:17 +0200 | [diff] [blame] | 180 | is the nonadjustable, high-resolution clock. |
| 181 | |
Victor Stinner | ca6e40f | 2012-04-28 23:47:33 +0200 | [diff] [blame] | 182 | Availability: Solaris. |
| 183 | |
Victor Stinner | 1470f35 | 2012-04-03 00:31:17 +0200 | [diff] [blame] | 184 | .. versionadded:: 3.3 |
| 185 | |
| 186 | |
Victor Stinner | e0be423 | 2011-10-25 13:06:09 +0200 | [diff] [blame] | 187 | .. data:: CLOCK_MONOTONIC |
| 188 | |
Georg Brandl | 514880c | 2012-04-30 12:50:30 +0200 | [diff] [blame] | 189 | Clock that cannot be set and represents monotonic time since some unspecified |
| 190 | starting point. |
Victor Stinner | e0be423 | 2011-10-25 13:06:09 +0200 | [diff] [blame] | 191 | |
Victor Stinner | ca6e40f | 2012-04-28 23:47:33 +0200 | [diff] [blame] | 192 | Availability: Unix. |
| 193 | |
Victor Stinner | e0be423 | 2011-10-25 13:06:09 +0200 | [diff] [blame] | 194 | .. versionadded:: 3.3 |
| 195 | |
Georg Brandl | 909f5bc | 2012-03-29 09:18:14 +0200 | [diff] [blame] | 196 | |
Victor Stinner | e0be423 | 2011-10-25 13:06:09 +0200 | [diff] [blame] | 197 | .. data:: CLOCK_MONOTONIC_RAW |
| 198 | |
| 199 | Similar to :data:`CLOCK_MONOTONIC`, but provides access to a raw |
| 200 | hardware-based time that is not subject to NTP adjustments. |
| 201 | |
| 202 | Availability: Linux 2.6.28 or later. |
| 203 | |
| 204 | .. versionadded:: 3.3 |
| 205 | |
Georg Brandl | 909f5bc | 2012-03-29 09:18:14 +0200 | [diff] [blame] | 206 | |
Victor Stinner | e0be423 | 2011-10-25 13:06:09 +0200 | [diff] [blame] | 207 | .. data:: CLOCK_PROCESS_CPUTIME_ID |
| 208 | |
| 209 | High-resolution per-process timer from the CPU. |
| 210 | |
Victor Stinner | ca6e40f | 2012-04-28 23:47:33 +0200 | [diff] [blame] | 211 | Availability: Unix. |
| 212 | |
Victor Stinner | e0be423 | 2011-10-25 13:06:09 +0200 | [diff] [blame] | 213 | .. versionadded:: 3.3 |
| 214 | |
Georg Brandl | 909f5bc | 2012-03-29 09:18:14 +0200 | [diff] [blame] | 215 | |
Victor Stinner | 6125e23 | 2012-04-12 21:40:14 +0200 | [diff] [blame] | 216 | .. data:: CLOCK_REALTIME |
| 217 | |
Georg Brandl | 514880c | 2012-04-30 12:50:30 +0200 | [diff] [blame] | 218 | System-wide real-time clock. Setting this clock requires appropriate |
Victor Stinner | 6125e23 | 2012-04-12 21:40:14 +0200 | [diff] [blame] | 219 | privileges. |
| 220 | |
Victor Stinner | ca6e40f | 2012-04-28 23:47:33 +0200 | [diff] [blame] | 221 | Availability: Unix. |
| 222 | |
Victor Stinner | 6125e23 | 2012-04-12 21:40:14 +0200 | [diff] [blame] | 223 | .. versionadded:: 3.3 |
| 224 | |
| 225 | |
Victor Stinner | e0be423 | 2011-10-25 13:06:09 +0200 | [diff] [blame] | 226 | .. data:: CLOCK_THREAD_CPUTIME_ID |
| 227 | |
| 228 | Thread-specific CPU-time clock. |
| 229 | |
Victor Stinner | ca6e40f | 2012-04-28 23:47:33 +0200 | [diff] [blame] | 230 | Availability: Unix. |
| 231 | |
Victor Stinner | e0be423 | 2011-10-25 13:06:09 +0200 | [diff] [blame] | 232 | .. versionadded:: 3.3 |
| 233 | |
Georg Brandl | 909f5bc | 2012-03-29 09:18:14 +0200 | [diff] [blame] | 234 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 235 | .. function:: ctime([secs]) |
| 236 | |
| 237 | Convert a time expressed in seconds since the epoch to a string representing |
| 238 | local time. If *secs* is not provided or :const:`None`, the current time as |
Petri Lehtinen | 1033b31 | 2012-05-18 21:19:17 +0300 | [diff] [blame] | 239 | returned by :func:`.time` is used. ``ctime(secs)`` is equivalent to |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 240 | ``asctime(localtime(secs))``. Locale information is not used by :func:`ctime`. |
| 241 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 242 | |
| 243 | .. data:: daylight |
| 244 | |
| 245 | Nonzero if a DST timezone is defined. |
| 246 | |
| 247 | |
Victor Stinner | ec89539 | 2012-04-29 02:41:27 +0200 | [diff] [blame] | 248 | .. function:: get_clock_info(name) |
| 249 | |
Victor Stinner | bda4b88 | 2012-06-12 22:11:44 +0200 | [diff] [blame] | 250 | Get information on the specified clock as a namespace object. |
Georg Brandl | 514880c | 2012-04-30 12:50:30 +0200 | [diff] [blame] | 251 | Supported clock names and the corresponding functions to read their value |
| 252 | are: |
Victor Stinner | ec89539 | 2012-04-29 02:41:27 +0200 | [diff] [blame] | 253 | |
Georg Brandl | 514880c | 2012-04-30 12:50:30 +0200 | [diff] [blame] | 254 | * ``'clock'``: :func:`time.clock` |
| 255 | * ``'monotonic'``: :func:`time.monotonic` |
| 256 | * ``'perf_counter'``: :func:`time.perf_counter` |
| 257 | * ``'process_time'``: :func:`time.process_time` |
| 258 | * ``'time'``: :func:`time.time` |
Victor Stinner | ec89539 | 2012-04-29 02:41:27 +0200 | [diff] [blame] | 259 | |
Victor Stinner | bda4b88 | 2012-06-12 22:11:44 +0200 | [diff] [blame] | 260 | The result has the following attributes: |
| 261 | |
Victor Stinner | 2b89fdf | 2012-06-12 22:46:37 +0200 | [diff] [blame] | 262 | - *adjustable*: ``True`` if the clock can be changed automatically (e.g. by |
| 263 | a NTP daemon) or manually by the system administrator, ``False`` otherwise |
Victor Stinner | bda4b88 | 2012-06-12 22:11:44 +0200 | [diff] [blame] | 264 | - *implementation*: The name of the underlying C function used to get |
| 265 | the clock value |
| 266 | - *monotonic*: ``True`` if the clock cannot go backward, |
| 267 | ``False`` otherwise |
| 268 | - *resolution*: The resolution of the clock in seconds (:class:`float`) |
| 269 | |
Victor Stinner | ec89539 | 2012-04-29 02:41:27 +0200 | [diff] [blame] | 270 | .. versionadded:: 3.3 |
| 271 | |
| 272 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 273 | .. function:: gmtime([secs]) |
| 274 | |
| 275 | Convert a time expressed in seconds since the epoch to a :class:`struct_time` in |
| 276 | UTC in which the dst flag is always zero. If *secs* is not provided or |
Petri Lehtinen | 1033b31 | 2012-05-18 21:19:17 +0300 | [diff] [blame] | 277 | :const:`None`, the current time as returned by :func:`.time` is used. Fractions |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 278 | of a second are ignored. See above for a description of the |
| 279 | :class:`struct_time` object. See :func:`calendar.timegm` for the inverse of this |
| 280 | function. |
| 281 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 282 | |
| 283 | .. function:: localtime([secs]) |
| 284 | |
| 285 | Like :func:`gmtime` but converts to local time. If *secs* is not provided or |
Petri Lehtinen | 1033b31 | 2012-05-18 21:19:17 +0300 | [diff] [blame] | 286 | :const:`None`, the current time as returned by :func:`.time` is used. The dst |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 287 | flag is set to ``1`` when DST applies to the given time. |
| 288 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 289 | |
Victor Stinner | 4195b5c | 2012-02-08 23:03:19 +0100 | [diff] [blame] | 290 | .. function:: mktime(t) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 291 | |
| 292 | This is the inverse function of :func:`localtime`. Its argument is the |
| 293 | :class:`struct_time` or full 9-tuple (since the dst flag is needed; use ``-1`` |
| 294 | as the dst flag if it is unknown) which expresses the time in *local* time, not |
Petri Lehtinen | 1033b31 | 2012-05-18 21:19:17 +0300 | [diff] [blame] | 295 | UTC. It returns a floating point number, for compatibility with :func:`.time`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 296 | If the input value cannot be represented as a valid time, either |
| 297 | :exc:`OverflowError` or :exc:`ValueError` will be raised (which depends on |
| 298 | whether the invalid value is caught by Python or the underlying C libraries). |
| 299 | The earliest date for which it can generate a time is platform-dependent. |
| 300 | |
| 301 | |
Victor Stinner | ec89539 | 2012-04-29 02:41:27 +0200 | [diff] [blame] | 302 | .. function:: monotonic() |
Victor Stinner | 8b30201 | 2012-02-07 23:29:46 +0100 | [diff] [blame] | 303 | |
Georg Brandl | 514880c | 2012-04-30 12:50:30 +0200 | [diff] [blame] | 304 | Return the value (in fractional seconds) of a monotonic clock, i.e. a clock |
| 305 | that cannot go backwards. The clock is not affected by system clock updates. |
| 306 | The reference point of the returned value is undefined, so that only the |
| 307 | difference between the results of consecutive calls is valid. |
Victor Stinner | ec919cc | 2012-03-15 00:58:32 +0100 | [diff] [blame] | 308 | |
Victor Stinner | ec89539 | 2012-04-29 02:41:27 +0200 | [diff] [blame] | 309 | On Windows versions older than Vista, :func:`monotonic` detects |
Georg Brandl | 514880c | 2012-04-30 12:50:30 +0200 | [diff] [blame] | 310 | :c:func:`GetTickCount` integer overflow (32 bits, roll-over after 49.7 days). |
Ezio Melotti | 99bafff | 2012-11-05 22:22:48 +0200 | [diff] [blame] | 311 | It increases an internal epoch (reference time) by 2\ :sup:`32` each time |
Georg Brandl | 514880c | 2012-04-30 12:50:30 +0200 | [diff] [blame] | 312 | that an overflow is detected. The epoch is stored in the process-local state |
| 313 | and so the value of :func:`monotonic` may be different in two Python |
Victor Stinner | ec89539 | 2012-04-29 02:41:27 +0200 | [diff] [blame] | 314 | processes running for more than 49 days. On more recent versions of Windows |
| 315 | and on other operating systems, :func:`monotonic` is system-wide. |
Victor Stinner | 8b30201 | 2012-02-07 23:29:46 +0100 | [diff] [blame] | 316 | |
Victor Stinner | ec89539 | 2012-04-29 02:41:27 +0200 | [diff] [blame] | 317 | Availability: Windows, Mac OS X, Linux, FreeBSD, OpenBSD, Solaris. |
| 318 | |
| 319 | .. versionadded:: 3.3 |
| 320 | |
| 321 | |
| 322 | .. function:: perf_counter() |
| 323 | |
Georg Brandl | 514880c | 2012-04-30 12:50:30 +0200 | [diff] [blame] | 324 | Return the value (in fractional seconds) of a performance counter, i.e. a |
| 325 | clock with the highest available resolution to measure a short duration. It |
| 326 | does include time elapsed during sleep and is system-wide. The reference |
| 327 | point of the returned value is undefined, so that only the difference between |
| 328 | the results of consecutive calls is valid. |
Victor Stinner | ec89539 | 2012-04-29 02:41:27 +0200 | [diff] [blame] | 329 | |
| 330 | .. versionadded:: 3.3 |
| 331 | |
| 332 | |
| 333 | .. function:: process_time() |
| 334 | |
Georg Brandl | 514880c | 2012-04-30 12:50:30 +0200 | [diff] [blame] | 335 | Return the value (in fractional seconds) of the sum of the system and user |
| 336 | CPU time of the current process. It does not include time elapsed during |
| 337 | sleep. It is process-wide by definition. The reference point of the |
| 338 | returned value is undefined, so that only the difference between the results |
| 339 | of consecutive calls is valid. |
Victor Stinner | 071eca3 | 2012-03-15 01:17:09 +0100 | [diff] [blame] | 340 | |
Victor Stinner | 0f7888d | 2012-02-14 02:42:21 +0100 | [diff] [blame] | 341 | .. versionadded:: 3.3 |
Victor Stinner | 8b30201 | 2012-02-07 23:29:46 +0100 | [diff] [blame] | 342 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 343 | .. function:: sleep(secs) |
| 344 | |
R David Murray | f1f9675 | 2015-01-25 15:45:14 -0500 | [diff] [blame] | 345 | Suspend execution of the calling thread for the given number of seconds. |
R David Murray | 1923b62 | 2015-01-25 15:46:22 -0500 | [diff] [blame] | 346 | The argument may be a floating point number to indicate a more precise sleep |
| 347 | time. The actual suspension time may be less than that requested because any |
| 348 | caught signal will terminate the :func:`sleep` following execution of that |
| 349 | signal's catching routine. Also, the suspension time may be longer than |
| 350 | requested by an arbitrary amount because of the scheduling of other activity |
| 351 | in the system. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 352 | |
| 353 | |
| 354 | .. function:: strftime(format[, t]) |
| 355 | |
| 356 | Convert a tuple or :class:`struct_time` representing a time as returned by |
| 357 | :func:`gmtime` or :func:`localtime` to a string as specified by the *format* |
| 358 | argument. If *t* is not provided, the current time as returned by |
| 359 | :func:`localtime` is used. *format* must be a string. :exc:`ValueError` is |
| 360 | raised if any field in *t* is outside of the allowed range. |
| 361 | |
Georg Brandl | 55ac8f0 | 2007-09-01 13:51:09 +0000 | [diff] [blame] | 362 | 0 is a legal argument for any position in the time tuple; if it is normally |
| 363 | illegal the value is forced to a correct one. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 364 | |
| 365 | The following directives can be embedded in the *format* string. They are shown |
| 366 | without the optional field width and precision specification, and are replaced |
| 367 | by the indicated characters in the :func:`strftime` result: |
| 368 | |
Georg Brandl | 55ac8f0 | 2007-09-01 13:51:09 +0000 | [diff] [blame] | 369 | +-----------+------------------------------------------------+-------+ |
| 370 | | Directive | Meaning | Notes | |
| 371 | +===========+================================================+=======+ |
| 372 | | ``%a`` | Locale's abbreviated weekday name. | | |
| 373 | | | | | |
| 374 | +-----------+------------------------------------------------+-------+ |
| 375 | | ``%A`` | Locale's full weekday name. | | |
| 376 | +-----------+------------------------------------------------+-------+ |
| 377 | | ``%b`` | Locale's abbreviated month name. | | |
| 378 | | | | | |
| 379 | +-----------+------------------------------------------------+-------+ |
| 380 | | ``%B`` | Locale's full month name. | | |
| 381 | +-----------+------------------------------------------------+-------+ |
| 382 | | ``%c`` | Locale's appropriate date and time | | |
| 383 | | | representation. | | |
| 384 | +-----------+------------------------------------------------+-------+ |
| 385 | | ``%d`` | Day of the month as a decimal number [01,31]. | | |
| 386 | | | | | |
| 387 | +-----------+------------------------------------------------+-------+ |
| 388 | | ``%H`` | Hour (24-hour clock) as a decimal number | | |
| 389 | | | [00,23]. | | |
| 390 | +-----------+------------------------------------------------+-------+ |
| 391 | | ``%I`` | Hour (12-hour clock) as a decimal number | | |
| 392 | | | [01,12]. | | |
| 393 | +-----------+------------------------------------------------+-------+ |
| 394 | | ``%j`` | Day of the year as a decimal number [001,366]. | | |
| 395 | | | | | |
| 396 | +-----------+------------------------------------------------+-------+ |
| 397 | | ``%m`` | Month as a decimal number [01,12]. | | |
| 398 | | | | | |
| 399 | +-----------+------------------------------------------------+-------+ |
| 400 | | ``%M`` | Minute as a decimal number [00,59]. | | |
| 401 | | | | | |
| 402 | +-----------+------------------------------------------------+-------+ |
| 403 | | ``%p`` | Locale's equivalent of either AM or PM. | \(1) | |
| 404 | | | | | |
| 405 | +-----------+------------------------------------------------+-------+ |
| 406 | | ``%S`` | Second as a decimal number [00,61]. | \(2) | |
| 407 | | | | | |
| 408 | +-----------+------------------------------------------------+-------+ |
| 409 | | ``%U`` | Week number of the year (Sunday as the first | \(3) | |
| 410 | | | day of the week) as a decimal number [00,53]. | | |
| 411 | | | All days in a new year preceding the first | | |
| 412 | | | Sunday are considered to be in week 0. | | |
| 413 | | | | | |
| 414 | | | | | |
| 415 | | | | | |
| 416 | +-----------+------------------------------------------------+-------+ |
| 417 | | ``%w`` | Weekday as a decimal number [0(Sunday),6]. | | |
| 418 | | | | | |
| 419 | +-----------+------------------------------------------------+-------+ |
| 420 | | ``%W`` | Week number of the year (Monday as the first | \(3) | |
| 421 | | | day of the week) as a decimal number [00,53]. | | |
| 422 | | | All days in a new year preceding the first | | |
| 423 | | | Monday are considered to be in week 0. | | |
| 424 | | | | | |
| 425 | | | | | |
| 426 | | | | | |
| 427 | +-----------+------------------------------------------------+-------+ |
| 428 | | ``%x`` | Locale's appropriate date representation. | | |
| 429 | | | | | |
| 430 | +-----------+------------------------------------------------+-------+ |
| 431 | | ``%X`` | Locale's appropriate time representation. | | |
| 432 | | | | | |
| 433 | +-----------+------------------------------------------------+-------+ |
| 434 | | ``%y`` | Year without century as a decimal number | | |
| 435 | | | [00,99]. | | |
| 436 | +-----------+------------------------------------------------+-------+ |
Alexander Belopolsky | 03163ac | 2011-05-02 12:20:52 -0400 | [diff] [blame] | 437 | | ``%Y`` | Year with century as a decimal number. | | |
Georg Brandl | 55ac8f0 | 2007-09-01 13:51:09 +0000 | [diff] [blame] | 438 | | | | | |
| 439 | +-----------+------------------------------------------------+-------+ |
Alexander Belopolsky | c142bba | 2012-06-13 22:15:26 -0400 | [diff] [blame] | 440 | | ``%z`` | Time zone offset indicating a positive or | | |
| 441 | | | negative time difference from UTC/GMT of the | | |
| 442 | | | form +HHMM or -HHMM, where H represents decimal| | |
| 443 | | | hour digits and M represents decimal minute | | |
| 444 | | | digits [-23:59, +23:59]. | | |
| 445 | +-----------+------------------------------------------------+-------+ |
Georg Brandl | 55ac8f0 | 2007-09-01 13:51:09 +0000 | [diff] [blame] | 446 | | ``%Z`` | Time zone name (no characters if no time zone | | |
| 447 | | | exists). | | |
| 448 | +-----------+------------------------------------------------+-------+ |
| 449 | | ``%%`` | A literal ``'%'`` character. | | |
| 450 | +-----------+------------------------------------------------+-------+ |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 451 | |
| 452 | Notes: |
| 453 | |
| 454 | (1) |
| 455 | When used with the :func:`strptime` function, the ``%p`` directive only affects |
| 456 | the output hour field if the ``%I`` directive is used to parse the hour. |
| 457 | |
| 458 | (2) |
Alexander Belopolsky | 9971e00 | 2011-01-10 22:56:14 +0000 | [diff] [blame] | 459 | The range really is ``0`` to ``61``; value ``60`` is valid in |
| 460 | timestamps representing leap seconds and value ``61`` is supported |
| 461 | for historical reasons. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 462 | |
| 463 | (3) |
| 464 | When used with the :func:`strptime` function, ``%U`` and ``%W`` are only used in |
| 465 | calculations when the day of the week and the year are specified. |
| 466 | |
| 467 | Here is an example, a format for dates compatible with that specified in the |
| 468 | :rfc:`2822` Internet email standard. [#]_ :: |
| 469 | |
| 470 | >>> from time import gmtime, strftime |
| 471 | >>> strftime("%a, %d %b %Y %H:%M:%S +0000", gmtime()) |
| 472 | 'Thu, 28 Jun 2001 14:17:15 +0000' |
| 473 | |
Georg Brandl | b7117af | 2013-10-13 18:28:25 +0200 | [diff] [blame] | 474 | Additional directives may be supported on certain platforms, but only the |
| 475 | ones listed here have a meaning standardized by ANSI C. To see the full set |
| 476 | of format codes supported on your platform, consult the :manpage:`strftime(3)` |
| 477 | documentation. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 478 | |
| 479 | On some platforms, an optional field width and precision specification can |
| 480 | immediately follow the initial ``'%'`` of a directive in the following order; |
| 481 | this is also not portable. The field width is normally 2 except for ``%j`` where |
| 482 | it is 3. |
| 483 | |
| 484 | |
| 485 | .. function:: strptime(string[, format]) |
| 486 | |
Brett Cannon | 7f6b4f8 | 2009-03-30 21:30:26 +0000 | [diff] [blame] | 487 | Parse a string representing a time according to a format. The return value |
| 488 | is a :class:`struct_time` as returned by :func:`gmtime` or |
| 489 | :func:`localtime`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 490 | |
| 491 | The *format* parameter uses the same directives as those used by |
| 492 | :func:`strftime`; it defaults to ``"%a %b %d %H:%M:%S %Y"`` which matches the |
Brett Cannon | 7f6b4f8 | 2009-03-30 21:30:26 +0000 | [diff] [blame] | 493 | formatting returned by :func:`ctime`. If *string* cannot be parsed according |
| 494 | to *format*, or if it has excess data after parsing, :exc:`ValueError` is |
| 495 | raised. The default values used to fill in any missing data when more |
| 496 | accurate values cannot be inferred are ``(1900, 1, 1, 0, 0, 0, 0, 1, -1)``. |
| 497 | Both *string* and *format* must be strings. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 498 | |
Christian Heimes | fe337bf | 2008-03-23 21:54:12 +0000 | [diff] [blame] | 499 | For example: |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 500 | |
| 501 | >>> import time |
Christian Heimes | fe337bf | 2008-03-23 21:54:12 +0000 | [diff] [blame] | 502 | >>> time.strptime("30 Nov 00", "%d %b %y") # doctest: +NORMALIZE_WHITESPACE |
| 503 | time.struct_time(tm_year=2000, tm_mon=11, tm_mday=30, tm_hour=0, tm_min=0, |
| 504 | tm_sec=0, tm_wday=3, tm_yday=335, tm_isdst=-1) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 505 | |
| 506 | Support for the ``%Z`` directive is based on the values contained in ``tzname`` |
| 507 | and whether ``daylight`` is true. Because of this, it is platform-specific |
| 508 | except for recognizing UTC and GMT which are always known (and are considered to |
| 509 | be non-daylight savings timezones). |
| 510 | |
| 511 | Only the directives specified in the documentation are supported. Because |
| 512 | ``strftime()`` is implemented per platform it can sometimes offer more |
| 513 | directives than those listed. But ``strptime()`` is independent of any platform |
| 514 | and thus does not necessarily support all directives available that are not |
| 515 | documented as supported. |
| 516 | |
| 517 | |
Georg Brandl | b67878a | 2010-10-15 17:01:15 +0000 | [diff] [blame] | 518 | .. class:: struct_time |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 519 | |
| 520 | The type of the time value sequence returned by :func:`gmtime`, |
Georg Brandl | b67878a | 2010-10-15 17:01:15 +0000 | [diff] [blame] | 521 | :func:`localtime`, and :func:`strptime`. It is an object with a :term:`named |
| 522 | tuple` interface: values can be accessed by index and by attribute name. The |
| 523 | following values are present: |
| 524 | |
| 525 | +-------+-------------------+---------------------------------+ |
| 526 | | Index | Attribute | Values | |
| 527 | +=======+===================+=================================+ |
| 528 | | 0 | :attr:`tm_year` | (for example, 1993) | |
| 529 | +-------+-------------------+---------------------------------+ |
| 530 | | 1 | :attr:`tm_mon` | range [1, 12] | |
| 531 | +-------+-------------------+---------------------------------+ |
| 532 | | 2 | :attr:`tm_mday` | range [1, 31] | |
| 533 | +-------+-------------------+---------------------------------+ |
| 534 | | 3 | :attr:`tm_hour` | range [0, 23] | |
| 535 | +-------+-------------------+---------------------------------+ |
| 536 | | 4 | :attr:`tm_min` | range [0, 59] | |
| 537 | +-------+-------------------+---------------------------------+ |
Alexander Belopolsky | 04da1e0 | 2011-01-10 19:14:38 +0000 | [diff] [blame] | 538 | | 5 | :attr:`tm_sec` | range [0, 61]; see **(2)** in | |
Georg Brandl | b67878a | 2010-10-15 17:01:15 +0000 | [diff] [blame] | 539 | | | | :func:`strftime` description | |
| 540 | +-------+-------------------+---------------------------------+ |
| 541 | | 6 | :attr:`tm_wday` | range [0, 6], Monday is 0 | |
| 542 | +-------+-------------------+---------------------------------+ |
| 543 | | 7 | :attr:`tm_yday` | range [1, 366] | |
| 544 | +-------+-------------------+---------------------------------+ |
| 545 | | 8 | :attr:`tm_isdst` | 0, 1 or -1; see below | |
| 546 | +-------+-------------------+---------------------------------+ |
Alexander Belopolsky | c142bba | 2012-06-13 22:15:26 -0400 | [diff] [blame] | 547 | | N/A | :attr:`tm_zone` | abbreviation of timezone name | |
| 548 | +-------+-------------------+---------------------------------+ |
Alexander Belopolsky | 93c9cd0 | 2012-06-22 16:04:19 -0400 | [diff] [blame] | 549 | | N/A | :attr:`tm_gmtoff` | offset east of UTC in seconds | |
Alexander Belopolsky | c142bba | 2012-06-13 22:15:26 -0400 | [diff] [blame] | 550 | +-------+-------------------+---------------------------------+ |
Georg Brandl | b67878a | 2010-10-15 17:01:15 +0000 | [diff] [blame] | 551 | |
| 552 | Note that unlike the C structure, the month value is a range of [1, 12], not |
Alexander Belopolsky | 03163ac | 2011-05-02 12:20:52 -0400 | [diff] [blame] | 553 | [0, 11]. A ``-1`` argument as the daylight |
Georg Brandl | b67878a | 2010-10-15 17:01:15 +0000 | [diff] [blame] | 554 | savings flag, passed to :func:`mktime` will usually result in the correct |
| 555 | daylight savings state to be filled in. |
| 556 | |
| 557 | When a tuple with an incorrect length is passed to a function expecting a |
| 558 | :class:`struct_time`, or having elements of the wrong type, a |
| 559 | :exc:`TypeError` is raised. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 560 | |
Alexander Belopolsky | c142bba | 2012-06-13 22:15:26 -0400 | [diff] [blame] | 561 | .. versionchanged:: 3.3 |
Andrew Svetlov | 3934b61 | 2012-10-04 19:52:32 +0300 | [diff] [blame] | 562 | :attr:`tm_gmtoff` and :attr:`tm_zone` attributes are available on platforms |
Georg Brandl | 61063cc | 2012-06-24 22:48:30 +0200 | [diff] [blame] | 563 | with C library supporting the corresponding fields in ``struct tm``. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 564 | |
Victor Stinner | 4195b5c | 2012-02-08 23:03:19 +0100 | [diff] [blame] | 565 | .. function:: time() |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 566 | |
R David Murray | 38c2754 | 2012-03-15 03:06:15 -0400 | [diff] [blame] | 567 | Return the time in seconds since the epoch as a floating point number. |
| 568 | Note that even though the time is always returned as a floating point |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 569 | number, not all systems provide time with a better precision than 1 second. |
| 570 | While this function normally returns non-decreasing values, it can return a |
| 571 | lower value than a previous call if the system clock has been set back between |
| 572 | the two calls. |
| 573 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 574 | .. data:: timezone |
| 575 | |
| 576 | The offset of the local (non-DST) timezone, in seconds west of UTC (negative in |
| 577 | most of Western Europe, positive in the US, zero in the UK). |
| 578 | |
| 579 | |
| 580 | .. data:: tzname |
| 581 | |
| 582 | A tuple of two strings: the first is the name of the local non-DST timezone, the |
| 583 | second is the name of the local DST timezone. If no DST timezone is defined, |
| 584 | the second string should not be used. |
| 585 | |
| 586 | |
| 587 | .. function:: tzset() |
| 588 | |
| 589 | Resets the time conversion rules used by the library routines. The environment |
| 590 | variable :envvar:`TZ` specifies how this is done. |
| 591 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 592 | Availability: Unix. |
| 593 | |
| 594 | .. note:: |
| 595 | |
| 596 | Although in many cases, changing the :envvar:`TZ` environment variable may |
| 597 | affect the output of functions like :func:`localtime` without calling |
| 598 | :func:`tzset`, this behavior should not be relied on. |
| 599 | |
| 600 | The :envvar:`TZ` environment variable should contain no whitespace. |
| 601 | |
| 602 | The standard format of the :envvar:`TZ` environment variable is (whitespace |
| 603 | added for clarity):: |
| 604 | |
| 605 | std offset [dst [offset [,start[/time], end[/time]]]] |
| 606 | |
| 607 | Where the components are: |
| 608 | |
| 609 | ``std`` and ``dst`` |
| 610 | Three or more alphanumerics giving the timezone abbreviations. These will be |
| 611 | propagated into time.tzname |
| 612 | |
| 613 | ``offset`` |
| 614 | The offset has the form: ``± hh[:mm[:ss]]``. This indicates the value |
| 615 | added the local time to arrive at UTC. If preceded by a '-', the timezone |
| 616 | is east of the Prime Meridian; otherwise, it is west. If no offset follows |
| 617 | dst, summer time is assumed to be one hour ahead of standard time. |
| 618 | |
| 619 | ``start[/time], end[/time]`` |
| 620 | Indicates when to change to and back from DST. The format of the |
| 621 | start and end dates are one of the following: |
| 622 | |
| 623 | :samp:`J{n}` |
| 624 | The Julian day *n* (1 <= *n* <= 365). Leap days are not counted, so in |
| 625 | all years February 28 is day 59 and March 1 is day 60. |
| 626 | |
| 627 | :samp:`{n}` |
| 628 | The zero-based Julian day (0 <= *n* <= 365). Leap days are counted, and |
| 629 | it is possible to refer to February 29. |
| 630 | |
| 631 | :samp:`M{m}.{n}.{d}` |
| 632 | The *d*'th day (0 <= *d* <= 6) or week *n* of month *m* of the year (1 |
| 633 | <= *n* <= 5, 1 <= *m* <= 12, where week 5 means "the last *d* day in |
| 634 | month *m*" which may occur in either the fourth or the fifth |
| 635 | week). Week 1 is the first week in which the *d*'th day occurs. Day |
| 636 | zero is Sunday. |
| 637 | |
| 638 | ``time`` has the same format as ``offset`` except that no leading sign |
| 639 | ('-' or '+') is allowed. The default, if time is not given, is 02:00:00. |
| 640 | |
| 641 | :: |
| 642 | |
| 643 | >>> os.environ['TZ'] = 'EST+05EDT,M4.1.0,M10.5.0' |
| 644 | >>> time.tzset() |
| 645 | >>> time.strftime('%X %x %Z') |
| 646 | '02:07:36 05/08/03 EDT' |
| 647 | >>> os.environ['TZ'] = 'AEST-10AEDT-11,M10.5.0,M3.5.0' |
| 648 | >>> time.tzset() |
| 649 | >>> time.strftime('%X %x %Z') |
| 650 | '16:08:12 05/08/03 AEST' |
| 651 | |
| 652 | On many Unix systems (including \*BSD, Linux, Solaris, and Darwin), it is more |
| 653 | convenient to use the system's zoneinfo (:manpage:`tzfile(5)`) database to |
| 654 | specify the timezone rules. To do this, set the :envvar:`TZ` environment |
| 655 | variable to the path of the required timezone datafile, relative to the root of |
| 656 | the systems 'zoneinfo' timezone database, usually located at |
| 657 | :file:`/usr/share/zoneinfo`. For example, ``'US/Eastern'``, |
| 658 | ``'Australia/Melbourne'``, ``'Egypt'`` or ``'Europe/Amsterdam'``. :: |
| 659 | |
| 660 | >>> os.environ['TZ'] = 'US/Eastern' |
| 661 | >>> time.tzset() |
| 662 | >>> time.tzname |
| 663 | ('EST', 'EDT') |
| 664 | >>> os.environ['TZ'] = 'Egypt' |
| 665 | >>> time.tzset() |
| 666 | >>> time.tzname |
| 667 | ('EET', 'EEST') |
| 668 | |
| 669 | |
| 670 | .. seealso:: |
| 671 | |
| 672 | Module :mod:`datetime` |
| 673 | More object-oriented interface to dates and times. |
| 674 | |
| 675 | Module :mod:`locale` |
Terry Jan Reedy | b5e2e7e | 2013-04-03 12:34:57 -0400 | [diff] [blame] | 676 | Internationalization services. The locale setting affects the interpretation |
Terry Jan Reedy | 41459a9 | 2013-04-03 12:45:24 -0400 | [diff] [blame] | 677 | of many format specifiers in :func:`strftime` and :func:`strptime`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 678 | |
| 679 | Module :mod:`calendar` |
Serhiy Storchaka | bfdcd43 | 2013-10-13 23:09:14 +0300 | [diff] [blame] | 680 | General calendar-related functions. :func:`~calendar.timegm` is the |
| 681 | inverse of :func:`gmtime` from this module. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 682 | |
| 683 | .. rubric:: Footnotes |
| 684 | |
| 685 | .. [#] The use of ``%Z`` is now deprecated, but the ``%z`` escape that expands to the |
| 686 | preferred hour/minute offset is not supported by all ANSI C libraries. Also, a |
| 687 | strict reading of the original 1982 :rfc:`822` standard calls for a two-digit |
| 688 | year (%y rather than %Y), but practice moved to 4-digit years long before the |
Sandro Tosi | f693810 | 2011-08-19 18:40:21 +0200 | [diff] [blame] | 689 | year 2000. After that, :rfc:`822` became obsolete and the 4-digit year has |
| 690 | been first recommended by :rfc:`1123` and then mandated by :rfc:`2822`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 691 | |