C:\test>type fred.pl
$exp = qr|^DMSC0022\s+\S+\s+(\w+)$|;
$str = 'Logfile_Connection_Lost Hostname: $1'; # note that you have to use single quotes or the $1 is interpolated as soon as you de
fine $str, not when you eval() the string (which is completely superfluous)
$_ = "DMSC0022 X10 oswald";
if ($exp)
 {
  print eval $str; # *now* get $str to interpolate
 }

C:\test>fred
Use of uninitialized value in print at C:\test\fred.pl line 6.

C:\test>