use IO::File;
my $fh = new IO::File;
$fh->open("<$usrhash") or die ......;
$fh->untaint();
flock($fh, LOCK_SH) or die..........;
$/=undef;
eval <$fh>;
$fh->close();
$/="\n"; 
my %newhash=%$USRLST1; # the reference as created by Data::Dumper