Here's an approach to use if you have all the 'log lines' as a single (possibly quite long) string as mention of  KEY.*PATTERN in your OP suggests: 

>perl -wMstrict -le
"my $s = 'KE a KE bb ccc KE ddd PA ee KE fff xx PA gg KEPA h';
 my $start     = qr{ KE }xms;
 my $not_start = qr{ (?! $start) . }xms;
 my $stop      = qr{ PA }xms;
 my $chunk     = qr{ $start $not_start* $stop }xms;
 print qq{'$s'};
 print map qq{'$_' }, $s =~ m{ $chunk }xmsg;
"
'KE a KE bb ccc KE ddd PA ee KE fff xx PA gg KEPA h'
'KE ddd PA' 'KE fff xx PA' 'KEPA'

[download]

This won't work if you are processing the file line-by-line. I'm working on that as, no doubt, are others.

Update: ... like toolic.

It should be mentioned that if if you are processing a multi-line file slurp, the  $start and  $stop regexes should be something like  qr{ ^ KE $ }xms and  qr{ ^ PA $ }xms respectively – note the  ^ $ embedded newline anchor metacharacters.

In reply to Re: pattern matching (greedy, non-greedy,...) by AnomalousMonk
in thread pattern matching (greedy, non-greedy,...) by cacophony777

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