I am new to Perl and working my way through one of the more popular Learning Perl Books. It usually takes me a while, but I can usually figure out why a certain piece of code in the Example sections works, but this time I am just not sure why. Here is the code: 
#!/usr/bin/perl
use strict;
use warnings;
use 5.010;

die "No file names supplied!\n" unless @ARGV;
my $oldest_name = shift @ARGV;
my $oldest_age = -M $oldest_name;
        foreach (@ARGV) {
        my $age = -M;
        ($oldest_name, $oldest_age) = ($_, $age)
                if $age > $oldest_age;
}

printf "The oldest file was %s, and it was %.1f days old\n",
        $oldest_name, $oldest_age;

[download]
How does $age know to apply -M to the file going through the foreach loop?

In reply to First Question, why something works? (-M) by i255d

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