REGEXP MATCH BASH

Find blocked messages 

grep -E "Blocked SPAM" /var/log/maillog | grep -v grep | awk 'match($0,/<[0-9a-z.]{1,}@[][0-9a-z.]{1,}> -> <[0-9a-z.]{1,}@[][0-9a-z.]{1,}>/) {print substr($0,RSTART,RLENGTH)}'

grep "SIP/gsm" checker.log.2022-09-* | awk 'match($0, /: load [0-9]*/) {print substr($0,RSTART,RLENGTH)}' | awk 'match($0, /[0-9]*$/) {print substr($0,RSTART,RLENGTH)}' | awk 'n < $0 {n=$0}END{print n}'