It’s never too late to answer a question.
Using netstat -tln, not netstat -at.
It’s very simple to answer, if you notify the --numeric option for netstat. By using this option, netstat will print address with numbers instead of meaningful string. Then you can grep them as you mentioned. Following shows how it works.
[root@A01-R26-I52-155-3002023 ~]# netstat -tl
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 localhost.localdom:smux 0.0.0.0:* LISTEN
tcp 0 0 localhost.localdo:18121 0.0.0.0:* LISTEN
tcp 0 0 localhost.localdo:18122 0.0.0.0:* LISTEN
tcp 0 0 localhost.localdo:18123 0.0.0.0:* LISTEN
tcp 0 0 localhost.localdo:18124 0.0.0.0:* LISTEN
tcp 0 0 localhost.localdo:18125 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:sunrpc 0.0.0.0:* LISTEN
tcp 0 0 localhost.localdo:18928 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:20080 0.0.0.0:* LISTEN
tcp 0 0 A01-R26-:univ-appserver 0.0.0.0:* LISTEN
tcp 0 0 A01-R26-:univ-appserver 0.0.0.0:* LISTEN
tcp 0 0 localhost.:search-agent 0.0.0.0:* LISTEN
tcp 0 0 localhost:mosaicsyssvc1 0.0.0.0:* LISTEN
tcp 0 0 A01-R26-I52-155-300:ssh 0.0.0.0:* LISTEN
tcp6 0 0 [::]:37611 [::]:* LISTEN
tcp6 0 0 [::]:sunrpc [::]:* LISTEN
tcp6 0 0 [::]:microsan [::]:* LISTEN
tcp6 0 0 [::]:commtact-http [::]:* LISTEN
[root@A01-R26-I52-155-3002023 ~]# netstat -tln
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 127.0.0.1:199 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:18121 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:18122 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:18123 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:18124 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:18125 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:18928 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:20080 0.0.0.0:* LISTEN
tcp 0 0 10.217.52.155:1233 0.0.0.0:* LISTEN
tcp 0 0 10.218.52.155:1233 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:1234 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:1235 0.0.0.0:* LISTEN
tcp 0 0 10.217.52.155:22 0.0.0.0:* LISTEN
tcp6 0 0 :::37611 :::* LISTEN
tcp6 0 0 :::111 :::* LISTEN
tcp6 0 0 :::20001 :::* LISTEN
tcp6 0 0 :::20002 :::* LISTEN