open FH, '/etc/passwd' or die "Can't open /etc/passwd, $!";
my @matches = grep { chomp; /thing_to_match/ } <FH>;

##</code><code>##

while (<FH>) {
   chomp;
   my ($name, $passwd, $uid, $gid, $quota, $comment,
       $gcos, $dir, $shell) = split /:/;
}

##</code><code>##

sub my_getpwnam {
   my $name_m = shift;
   open FH, '/etc/passwd' or die "Can't open /etc/passwd, $!";
   
   my @match = grep { chomp; /^$name_m:/ } <FH>;
   if (!@match) { return (); }  # return empty list if not found
   return split /:/, $match[0];
}