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Mark Overmeer
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POSIX::1003::Time - POSIX handling time


  use POSIX::1003::Time;

  tzset();      # set-up local timezone from $ENV{TZ}
  ($std, $dst) = tzname;  # timezone abbreviations

  $str = ctime($timestamp);   # is equivalent to:
  $str = asctime(localtime($timestamp))

  $str = strftime("%A, %B %d, %Y", 0, 0, 0, 12, 11, 95, 2);
  $str = strftime("%A, %B %d, %Y", {day => 12, month => 12
    , year => 1995, wday => 2});
  # $str contains "Tuesday, December 12, 1995"

  $timestamp = mktime(0, 30, 10, 12, 11, 95);
  $timestamp = mktime {min => 30, hour => 10, day => 12
    , month => 12, year => 1995};
  print "Date = ", ctime($timestamp);

  print scalar localtime;
  my $year   = (localtime)[5] + 1900;

  $timespan  = difftime($end, $begin);



Standard POSIX

Warning: the functions asctime(), mktime(), and strftime() share a weird complex encoding with localtime() and gmtime(): the month (mon), weekday (wday), and yearday (yday) begin at zero. I.e. January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1. The year (year) is given in years since 1900. I.e., the year 1995 is 95; the year 2001 is 101.

asctime($sec, $min, $hour, $mday, $mon, $year, ...)

The asctime function uses strftime with a fixed format, to produce timestamps with a trailing new-line. Example:

  "Sun Sep 16 01:03:52 1973\n"

The parameter order is the same as for strftime() without its $format parameter:

  my $str = asctime($sec, $min, $hour, $mday, $mon, $year,
                 $wday, $yday, $isdst);

The amount of spent processor time in microseconds.

  # equivalent
  my $str = ctime $timestamp;
  my $str = asctime localtime $timestamp;
difftime($timestamp, $timestamp)

Difference between two TIMESTAMPs, which are floats.

  $timespan = difftime($end, $begin);
gmtime( [$time] )

Simply "gmtime" in perlfunc

localtime( [$time] )

Simply "localtime" in perlfunc


Convert date/time info to a calendar time. Returns "undef" on failure.

  # Calendar time for December 12, 1995, at 10:30 am
  my $ts = mktime 0, 30, 10, 12, 11, 95;
  print "Date = ", ctime($ts);

  my %tm = (min => 30, hour => 10, day => 12, month => 12, year => 1995);
  my $ts = mktime \%tm;   # %tm will get updated, mday and yday added
strftime($format, @tm|\%date)

The formatting of strftime is extremely flexible but the parameters are quite tricky. Read carefully!

  my $str = strftime($fmt, $sec, $min, $hour,
      $mday, $mon, $year, $wday, $yday, $isdst);

  my $str = strftime($fmt, {month => 12, year => 2015};

If you want your code to be portable, your $format argument should use only the conversion specifiers defined by the ANSI C standard (C89, to play safe). These are aAbBcdHIjmMpSUwWxXyYZ%. But even then, the results of some of the conversion specifiers are non-portable.

[0.95_5] This implementation of strftime() is character-set aware, even when the LC_TIME table does not match the type of the format string.

strptime($timestring, $format)

Translate the TIMESTRING into a time-stamp (seconds since epoch). The $format describes how the $timestring should be interpreted.

Returned is a HASH with the usefull data from the 'tm' structure (as described in the standard strptime manual page) The keys are stripped from the tm_ prefix.


   # traditional interface
   my ($sec, $min, ...) = strptime "12:24", "%H:%S";

   # date as hash
   my $tm = strptime "12:24", "%H:%S";
   print "$tm->{hour}/$tm->{min}\n";
   my $time = mktime $tm;

Returns the strings to be used to represent Standard time (STD) respectively Daylight Savings Time (DST).

  my ($std, $dst) = tzname;

Set-up local timezone from $ENV{TZ} and the OS.


The constant names for this module are inserted here during installation.


This module is part of POSIX-1003 distribution version 1.00, built on May 05, 2020. Website: http://perl.overmeer.net/CPAN. The code is based on POSIX, which is released with Perl itself. See also POSIX::Util for additional functionality.


Copyrights 2011-2020 on the perl code and the related documentation by [Mark Overmeer]. For other contributors see ChangeLog.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See http://dev.perl.org/licenses/