in reply to Print only if pattern matches

Place your matching regex in an if statement. If true, you can print your captures w/o error. The else can handle the exceptions:

use strict; use warnings; while (<DATA>) { next unless /^\d+\|(\d+?)\|/ and $1 == 1; if (/^(.*\|)*.*ABC\.pi=([\d.]+|[\w.]+)*.*ABC\.id=(\d+|[\w.]+).*$/) + { print "$1$2|$3\n"; } else { print "Exception: $_"; } }

Output on your data:

123|1|456464|645646|4546|112.33.44.55.66|789137136770 123|1|456464|645646|4546|112.33.44.55.67|789134713670 123|1|456464|645646|4546|112.33.44.55.68|789137213670 123|1|456464|645646|4546|112.33.44.55.69|78913713670 Exception: 123|1|456464|645646|4546|654~abc~dhghga~12.33.44.55.70~3713 +670 123|1|456464|645646|4546|112.33.44.55.70|78913713670 123|1|456464|645646|4546|112.33.44.55.70|78913713670 123|1|456464|645646|4546|112.33.44.55.70|789137135670 123|1|456464|645646|4546|112.33.44.55.70|789137153670 Exception: 123|1|456464|645646|4546|654~abc~dhghga~12.33.44.55.70~3713 +670 Exception: 123|1|456464|645646|4546|654~abc~dhghga~121322~456466874~87 +96896