$elem is a lousy variable name, just as bad as $count.

I respectfully disagree. It's bad, but not as bad. $elem carries very little information; $count is actually misleading.

In such situations, I tend to use $_, which has the advantage of being known, a priori, as a list iterator, by virtue of its special relation to foreach and while(<>).

for ( "$year:$mon:$mday", "$hour:$min:$sec" )
{
    mkdir $_ or die "mkdir $_ - $!";
    chdir $_ or die "chdir $_ - $!";
}
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