I can think of twothree quick ways:

my $today = localtime;
my ($day) = $today =~ m/^(\w{3})/;
[download]

my $dow = qw(Sun Mon Tue Wed Thu Fri Sat)[(localtime())[6]];
and

use POSIX qw(strftime);
my $dow = strftime "%a", localtime;
[download]

Update: Added third method.