Built-in Module time

time This module provides various time-related functions. It is always available. An explanation of some terminology and conventions is in order.

The ``epoch'' is the point where the time starts. On January 1st of that year, at 0 hours, the ``time since the epoch'' is zero. For UNIX, the epoch is 1970. To find out what the epoch is, look at the first element of gmtime(0).
UTC is Coordinated Universal Time (formerly known as Greenwich Mean Time). The acronym UTC is not a mistake but a compromise between English and French.
DST is Daylight Saving Time, an adjustment of the timezone by (usually) one hour during part of the year. DST rules are magic (determined by local law) and can change from year to year. The C library has a table containing the local rules (often it is read from a system file for flexibility) and is the only source of True Wisdom in this respect.
The precision of the various real-time functions may be less than suggested by the units in which their value or argument is expressed. E.g. on most UNIX systems, the clock ``ticks'' only every 1/50th or 1/100th of a second, and on the Mac, it ticks 60 times a second.

Functions and data items are:
$\begin{datadesc}{altzone} The offset of the local DST timezone, in seconds west ... ..., if one is defined. Only use this if \code{daylight} is nonzero. \end{datadesc}$

$\begin{funcdesc}{asctime}{tuple} Convert a tuple representing a time as returned... ...ke the C function of the same name, there is no trailing newline. \end{funcdesc}$

$\begin{funcdesc}{clock}{} Return the current CPU time as a floating point number... ...The precision depends on that of the C function by the same name. \end{funcdesc}$

$\begin{funcdesc}{ctime}{secs} Convert a time expressed in seconds since the epoc... ...e. \code{ctime(t)} is equivalent to \code{asctime(localtime(t))}. \end{funcdesc}$

$\begin{datadesc}{daylight} Nonzero if a DST timezone is defined. \end{datadesc}$

$\begin{funcdesc}{gmtime}{secs} Convert a time expressed in seconds since the epo... ...gnored. Note subtle differences with the C function of this name. \end{funcdesc}$

$\begin{funcdesc}{localtime}{secs} Like \code{gmtime} but converts to local time. The dst flag is set to 1 when DST applies to the given time. \end{funcdesc}$

$\begin{funcdesc}{mktime}{tuple} This is the inverse function of \code{localtime}... ...ll 9-tuple (since the dst flag is needed). It returns an integer. \end{funcdesc}$

$\begin{funcdesc}{sleep}{secs} Suspend execution for the given number of seconds.... ...be a floating point number to indicate a more precise sleep time. \end{funcdesc}$

$\begin{funcdesc}{time}{} Return the time as a floating point number expressed in... ...t all systems provide time with a better precision than 1 second. \end{funcdesc}$

$\begin{datadesc}{timezone} The offset of the local (non-DST) timezone, in second... ...e in most of Western Europe, positive in the US, zero in the UK). \end{datadesc}$

$\begin{datadesc}{tzname} A tuple of two strings: the first is the name of the lo... ...no DST timezone is defined, the second string should not be used. \end{datadesc}$