Much too complicated. Why generate a random character and then use a regex to delete it? Even Arien's good suggestion can be written briefer. 
my @pass_char = ('a'..'z', 'A'..'Z', 0 .. 9, qw(_ . @));
sub generate_password {
    my $len = shift || 12;
    my $pass;
    $pass .= $pass_char[rand @pass_char] for 1 .. $len;
    return $pass;
}

[download]
I can't resist golfing this a bit.. but the following is not necessarily for use in production. :-) 
my @pass_char = ('a'..'z', 'A'..'Z', 0 .. 9, qw(_ . @));
sub generate_password {
    return join '', map $pass_char[rand @pass_char], 1 .. (shift || 12
+);
}

[download]
____________
Makeshifts last the longest.

In reply to Re^2: String randomness by Aristotle
in thread String randomness by Anonymous Monk

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