use strict;
my $str = 'Sep 19 23:32:49 10.201.1.79 [pfsp] emerg: Host Detection alert #13630, start 2017-09-19 23:31:45 UTC, duration 64, direction incoming, host 1.2.3.4, signatures (IP Fragmentation, DNS Amplification), impact 1.10 Gbps/117.80 Kpps, importance 2, managed_objects ("ARIN-Allocated Prefixes"), (parent managed object "nil")
Sep 20 04:56:50 10.201.1.79 [pfsp] emerg: Host Detection alert #13631, start 2017-09-20 04:56:45 UTC, duration 5, direction incoming, host 1.2.3.4, signatures (IP Fragmentation), impact 133.45 Mbps/21.82 Kpps, importance 1, managed_objects ("ARIN-Allocated Prefixes"), (parent managed object "nil") ';
my $regex = qr/signatures\s\((?<signature_value>[^\)]+)\)/p;
if ( $str =~ /$regex/g ) {
print "Whole match is ${^MATCH} and its start/end positions can be obtained via \$-[0] and \$+[0]\n";
# print "Capture Group 1 is $1 and its start/end positions can be obtained via \$-[1] and \$+[1]\n";
# print "Capture Group 2 is $2 ... and so on\n";
}
# ${^POSTMATCH} and ${^PREMATCH} are also available with the use of '/p'
# Named capture groups can be called via $+{name}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html