Below script is to parse output from netstat -tulnp or ipvsadm -Ln.
#!/bin/bash
input=$1
vipNportRe="TCP ([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}:[0-9]{2,3}).*$"
ipNportRe=".*-> ([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}:[0-9]{2,3}).*$"
netstatIpNportRe="^tcp .* 0 ([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}:[0-9]{2,3}).*$"
while read line
do
if [[ $line =~ $ipNportRe ]]; then
echo "${BASH_REMATCH[1]}"
elif [[ $line =~ $netstatIpNportRe ]]; then
echo "${BASH_REMATCH[1]}"
fi
done < $input
# Get the lines in a.txt but not in b.txt
grep -F -x -v -f b.txt a.txt
