Re: change hour in timestamp

The Time::Piece module, along with its associated Time::Seconds module for date calculations, is core.

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
[download]

I hope that this is helpful.

Cheers,

JohnGG

Comment on Re: change hour in timestamp Download Code

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Re^2: change hour in timestamp
by kcott (Archbishop) on Jun 05, 2022 at 00:54 UTC

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 ~~name~~day 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);
[download]

which outputs:

Sat Jun  4 20:47:31 2022
Fri Jun 10 20:47:31 2022
[download]

— Ken

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