in reply to saving matching pattern with flip-flop operator
The second regex clears the capture from the first.
while (<DATA>) { if(/START/.../END TIME (.+)/) { my $time = $1; next if(/START/ | /^\s*$/); print $time, qq{\n}; } } __DATA__ START END TIME 123 START END TIME 456
123 456
In Section
Seekers of Perl Wisdom