What is the best way to make an array from a field within another array. I can split & iterate though, and get it working, but you folks often have a slicker way. your help is appreciated. Sorry for the unclear post. First, what I wish to accomplish is to locate unused entries in UNIX /etc/group files. This requires the fourth group file field to have no entries, and the second field to not appear in any fourth field of the /etc/passwd file. What I have so far handle the first part, but the second part is not working yet, ( and I need to negate the second part once it works.) 
#!/usr/bin/perl -w
#<UnusedGrp.pl> Find unused Groups in /etc/group

my $GROUPfile="/etc/group";
my $gfpid = open(GFILE, "<$GROUPfile") or die "$GROUPfile File Not Fou
+nd: $!\n";
my $PASSWD="/etc/passwd";
my $pfpid = open(PFILE, "<$PASSWD") or die "$PASSWD File Not Found: $!
+\n";
@PWLINES = <PFILE>;

while (my $line = <GFILE>) {
   @GRP = split(/:/, $line);
   if (length($GRP[3]) < 2){
     print "$GRP[0]:$GRP[2] is zero length\n";
     if ((@GREPED = grep(/\:\*\:${GRP[3]}\:/, @PWLINES))) {
       print @GREPED;
     }
     undef @GREPED;
   }
}

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