sub SERVER_NAME() { 0 }
sub DATE() { 1 }
# ...
sub ERROR_TYPE() { 4 }
# etc.

while( <msg> ) {
  chomp ;
  @elements = split /,/ ;
  if( $elements[ERROR_TYPE] eq 'ERROR' ) {
    # handle error
    next ;
  } 
}


##</code><code>##

use strict ;
use Storable ;
use FileHandle ;
my($hashRef, $log) ;


# program startup
# read previous data:
if( !-e 'myFile' ) {
   # myFile not found, assume we're starting from the beginning
    $hashRef->{lastPosition} = 0 ; # start at the beg
    # add other values as needed

}
else {
    $hashRef = retrieve('myFile') ;
}

$log = new FileHandle('logfile') ;
$log->seek($hashRef->{lastPosition}, 0) ; # go back to previous point searched

#############
## Process ##
#############

##
## save where the end of the file currently is, so 
## we don't have to scan the whole file again next time
##
$hashRef->{lastPosition} = $log->tell() ; # get file offset


##
## Store new state data
##
store $hashRef, 'myFile' ;