Keeping it simple, localtime returns the day of the week in list context as the field at index 6:

print [localtime]->[6], "\n";
# Outputs 2 for me, today, because it's Tuesday and weeks start at 0 f
+or Sunday.
[download]

So values of 0 or 6 would represent Sunday and Saturday.

Time::Piece, which comes with Perl, presents an object oriented interface into date/time manipulation:

use Time::Piece;
my $t = localtime;
print join(', ', $t->day_of_week, $t->day, $t->fullday), "\n";
# Outputs 2, Tue, Tuesday
[download]

However, you may also decide that it's a better separation of concerns, leading to more generally useful code if you let the code not care about the day of the week, and set up a crontab entry to do what cron does best.