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Re: Finding oldest file in directory

by Roy Johnson (Monsignor)
on Oct 18, 2004 at 19:12 UTC ( #400283=note: print w/ replies, xml ) Need Help??


in reply to Finding oldest file in directory

Finding the oldest/most recent/minimum/maximum of a list does not require sorting. For a 10-file directory, it's not a big deal, but the right tool for the job is a simple max-finder:

my $oldest; my $oldtime = 0; for (glob "$dir/*.pl") { my $thistime = -C; if ($thistime > $oldtime) { ($oldest, $oldtime) = ($_, $thistime); } }
You could do this at kind of the same programming level as you're trying to by using List::Util 'reduce':
use List::Util 'reduce'; my $file = (reduce {$a->[0] < $b->[0] ? $a : $b} map {[(stat)[10],$_]} glob '*.pl' )->[1];
That makes for somewhat complicated reading, though, and might be better broken into more steps.

Update: for posterity: the map above is only useful for reducing the number of times stat is called, from 2*N to N. The overhead of map and storing the values and dereferencing is probably not worth it. It's certainly simpler to say

my $file = reduce {(stat $a)[10] < (stat $b)[10] ? $a : $b} glob '*.pl';

Caution: Contents may have been coded under pressure.


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