Hi,

I suggest to use a parser to parse your string into a DateTime object. I also suggest to handle time zones properly and not just by subtracting a value from the hours. What will happen when you try that and the time is earlier than 02:00 ?

use strict;
use warnings;
use feature 'say';
use DateTime::Format::Strptime;

my $string = 'Sat Jun  4 01:47:31 2022';

my $parser = DateTime::Format::Strptime->new(
    pattern   => '%a %b %d %T %Y',
    locale    => 'en_US',
    time_zone => 'America/New_York',
    on_error  => 'croak',
);

my $datetime = $parser->parse_datetime($string);

$datetime->set_time_zone('America/Denver');

say $datetime->strftime('%a %b %d %T %Y');

__END__
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Hope this helps!

johngg@abouriou:~/perl/Monks$ perl -Mstrict -Mwarnings -MTime::Piece -
+MTime::Seconds -E 'say q{};
my $date = q{Sat Jun  4 22:47:31 2022};
my $tp   = Time::Piece->strptime( $date, q{%a %b %d %T %Y} );
$tp     -= ONE_HOUR;
$tp     -= ONE_HOUR;
say $tp->strftime();'

Sat, 04 Jun 2022 20:47:31 UTC
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I hope that this is helpful.

G'day JohnGG,

++ Upon reading the OP, I immediately thought of Time::Piece; then, after scrolling through the posts, I saw you'd used this already.

If I may, some minor improvements:

• Instead of decrementing $tp in two statements, you can do that in one: "$tp -= 2 * ONE_HOUR".
• Your output has a slightly different format to the OP's input: comma after day and introduced timezone. You can mostly fix that by using the same date format for the input and output.
  Update: On rereading, I also see the month name and day are swapped as are the time and year. The suggested fix handles both of those cases also.
• If the leading zero on the month nameday is a problem for the OP, you can fix that with sprintf. I added a "$tp += 6 * ONE_DAY" to test that.
  • Checking `man strptime` on my Cygwin platform, I see %d gives a two-digit string, padded with a zero for a single-digit month day. I couldn't find a format for that which doesn't pad with a zero. Assuming I didn't simply miss it, if one exists on another OS, it may not be portable.

Here's the updated code:

    my $date = q{Sat Jun  4 22:47:31 2022};
    my $fmt_t = q{%a %b %d %T %Y};
    my $fmt_s = q{%s %s %2d %s %d};
    my $tp = Time::Piece->strptime($date, $fmt_t);
    $tp -= 2 * ONE_HOUR;
    say sprintf $fmt_s, split q{ }, $tp->strftime($fmt_t);
    $tp += 6 * ONE_DAY;
    say sprintf $fmt_s, split q{ }, $tp->strftime($fmt_t);
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which outputs:

Sat Jun  4 20:47:31 2022
Fri Jun 10 20:47:31 2022
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— Ken

use DateTime::Format::Flexible;
sub date { DateTime::Format::Flexible->parse_datetime(shift); }

my $d= date('Sat Jun  4 22:47:31 2022');
$d->set_time_zone('+0200')->set_time_zone('UTC');
print "$d\n";
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DateTime says

Parsing Dates

This module does not parse dates! That means there is no constructor to which you can pass things like "March 3, 1970 12:34".

Instead, take a look at the various DateTime::Format::* modules on CPAN. These parse all sorts of different date formats, and you're bound to find something that can handle your particular needs.

I searched around in metacpan and found Date::Parse and the Synopsis seems to do the job well, at least for epoch

use strict;
use warnings;
use Data::Dump qw/pp dd/;
use Date::Parse;
use DateTime;

pp my $date = 'Sat Jun  4 22:47:31 2022';
pp my $time = str2time($date);

pp my ($ss,$mm,$hh,$day,$month,$year,$zone) = strptime($date);

my $dt = DateTime->from_epoch
  (
   epoch     => $time,
   time_zone => 'UTC',                  # fill in your timezone
  );

print $dt;
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"Sat Jun  4 22:47:31 2022"
1654375651
(31, 47, 22, 4, 5, 122, undef)
2022-06-04T20:47:31
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Other modules - especially the one suggested by 1nickt - might be better, I just wanted to demonstrate how to solve it by yourself.

Thank you for all the interesting answers. Another easy approach to achieve my OP:

use strict;
use warnings;
use Time::Piece;

my $date = "Sat Jun  4 22:47:31 2022 +0200";
my $fmt = '%a %b %d %T %Y %z';
my $tp = Time::Piece->strptime($date, $fmt);
print $tp;
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I agree with the mention that I should work with timezone though.