http://www.perlmonks.org?node_id=11120913


in reply to Downloading only new files added to a local path with Perl (FTP)

As an aside: 

# perl -e 'print time' will return the current time in Unix epoch form
+at

# So if you substract 43200, that should give you the current time min
+us 30 minutes in Unix epoch format:

time=$(perl -e 'print time-43200')

[download]

There are 86400 seconds in a day, so subtracting 43200 subtracts half a day. Subtract 1800 to go back half an hour. 

c:\@Work\Perl\monks>perl -wMstrict -le
"my $t = time;
 print $t;
 print scalar localtime $t;
 print scalar localtime $t - 43200;
 print scalar localtime $t -  1800;
"
1597857155
Wed Aug 19 13:12:35 2020
Wed Aug 19 01:12:35 2020
Wed Aug 19 12:42:35 2020

[download]
See time, localtime, gmtime.

Give a man a fish:  <%-{-{-{-<

In Section Seekers of Perl Wisdom