Hi Monks, I have a question. I am having a hard time understanding how hashes work, an example of the code below demonstrates what I am trying to accomplish. I am wondering howto take multiple comma delimited files (/etc/passwd) and take the unique ids(which is already present in another file) off of each file and push pop whatever them to append to a different file that already has the same ids present. Basically I have another file with the unique ids present already and from the /etc/passwd, named passwd.(server) files i want to list every passwd.server file that these unique ids from the existing file are on. What i want to know about the code below is line by line what is it doing? Thanks. 
#!/usr/bin/perl -w
use strict;
my %USERS;
foreach my $file (<passwd.*>) {
    open(PASSWD,$file);
    my $strip=$file;
    $strip =~ s/passwd\.//;
    while(<PASSWD>) {
        my($login,$gcos) = (split(':',$_))[0,4];

        if(exists $USERS{$login}) {
            push(@{$USERS{$login}},$strip);
        } else {
            $USERS{$login} = [$gcos,$strip];
        }
    }
    close(PASSWD);
}

open(NEWFILE,">endstrx") || print "Can't open servup: $!\n";
foreach my $login (sort keys %USERS) {
    print NEWFILE "$login:".shift(@{$USERS{$login}}).":";
    print NEWFILE join(':',@{$USERS{$login}})."\n";
}
close(NEWFILE);

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In reply to hash of hashes -newbie question? by tux242

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