Quickly getting to YYYY-mm-dd HH:MM:SS in Perl

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When writing Perl scripts I frequently find the need to obtain the current time represented as a string formatted as YYYY-mm-dd HH:MM:SS (say 2009-11-29 14:28:29).

In doing this I find myself taking this quite cumbersome path:

  • man perlfunc
  • /localtime to search for localtime - repeat five times (/ + \n) to reach the relevant section of the manpage
  • Copy the string ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time); from the manpage to my script.
  • Try with my $now = sprintf("%04d-%02d-%02d %02d:%02d:%02d", $year, $mon, $mday, $hour, $min, $sec);
  • Remember gotcha #1: Must add 1900 to $year to get current year.
  • Try with my $now = sprintf("%04d-%02d-%02d %02d:%02d:%02d", $year+1900, $mon, $mday, $hour, $min, $sec);
  • Remember gotcha #2: Must add 1 to $mon to get current month.
  • Try with my $now = sprintf("%04d-%02d-%02d %02d:%02d:%02d", $year+1900, $mon+1, $mday, $hour, $min, $sec);
  • Seems ok. Done!

While the process outlined above works it is far from optimal. I'm sure there is a smarter way, so my question is simply:

What is the easiest way to obtain a YYYY-mm-dd HH:MM:SS of the current date/time in Perl?

Where "easy" encompasses both "easy-to-write" and "easy-to-remember".

formatting perl timestamp datetime
9 Answers

In many cases, the needed 'current time' is rather $^T, which is the time at which the script started running, in whole seconds (assuming only 60 second minutes) since the UNIX epoch.

This to prevent that an early part of a script uses a different date (or daylight-saving status) than a later part of a script, for example in query-conditions and other derived values.

For that variant of 'current time', one can use a constant, also to document that it was frozen at compile time:

use constant YMD_HMS_AT_START => POSIX::strftime( "%F %T", localtime $^T );

Alternative higher resolution startup time:

0+ [ Time::HiRes::stat("/proc/$$") ]->[10]
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