Perl: Empty/broken AoH - arrays

Question

I have subroutine in my module which checks (regular) user password age using regex search on shadow file:
Module.pm
my $pwdsetts_dump = "tmp/shadow_dump.txt";
system("cat /etc/shadow > $pwdsetts_dump");
open (my $fh1, "<", $pwdsetts_dump) or die "Could not open file '$pwdsetts_dump': $!";
sub CollectPWDSettings {
my #pwdsettings;
while (my $array = <$fh1>) {
if ($array =~ /^(\S+)[:][$]\S+[:](1[0-9]{4})/) {
my $pwdchange = "$2";
if ("$2" eq "0") {
$pwdchange = "Next login";
}
my %hash = (
"Username" => $1,
"Last change" => $pwdchange
);
push (#pwdsettings, \%hash);
}
}
my $current_date = int(time()/86400); # epoch
my $ndate = shift #_; # n-days
my $search_date = int($current_date - $ndate);
my #sorted = grep{$_->{'Last change'} > $search_date} #pwdsettings;
return \#sorted;
}
Script is divided in 2 steps:
1. load all password settings
2. search for password which is older than n-days
In my main script I use following script:
my ($user_changed_pwd);
if (grep{$_->{'Username'} eq $users_to_check} #{Module::CollectPWDSettings("100")}) {
$user_changed_pwd = "no";
}
else {
$user_changed_pwd = "yes";
}
Problem occurs in first step, AoH never gets populated. I'm also pretty sure that this subroutine always worked for me and strict and warnings never complained about it, nut now, for some reason it refuses to work.

Answer 1

I've just run your regex against my /etc/shadow and got no matches. If I drop the leading 1 I get a few hits.
E.g.:
$array =~ /^(\S+)[:][$]\S+[:]([0-9]{4})/
But personally - I would suggest not trying to regex, and instead rely on the fact that /etc/shadow is defined as delimited by :.
my #fields = split ( /:/, $array );
$1 contains a bunch of stuff, and I suspect what you actually want is the username - but because \S+ is greedy, you might be accidentally ending up with encrypted passwords.
Which will be $fields[0].
And then the 'last change' field - from man shadow is $fields[2].

Answer 2

I think your regex pattern is the main problem. Don't forget that \S matches any non-space character including colons :, and \S+ will try to match as much as possible so it will happily skip over multiple fields of the file
I think using split to separate each record into colon-delimited fields is a better approach. I also think that, instead of the array of two-element hashes #pwdsettings it would be better to store the data as a hash relating usernames to their password history
Here's how I would write this. It prints a list of all usernames whose password history is greater than 90 days
use strict;
use warnings;
use Time::Seconds 'ONE_DAY';
my #shadow = do {
open my $fh, '<', '/etc/shadow' or die qq{Unable to open "/etc/shadow" for input: $!};
<$fh>;
};
print "$_\n" for #{ collect_pwd_settings(90) };
sub collect_pwd_settings {
my ($ndate) = #_;
my %pwdsettings;
for ( #shadow ) {
my ($user, $pwdchange) = (split /:/)[0,2];
$pwdsettings{$user} = $pwdchange;
}
my $current_date = time / ONE_DAY;
my #filtered = grep { $current_date - $pwdsettings{$_} > $ndate } keys %pwdsettings;
return \#filtered;
}