# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/(?s).*?(\z|\d+\.\d+\.\d+\.\d+)/$1\n/gm;t' <<< "Nmap scan report for 192.168.0.21
Host is up (0.18s latency).
Not shown: 1 filtered port
Some closed ports may be reported as filtered due to --defeat-rst-ratelimit
PORT STATE SERVICE
22/tcp open ssh
Nmap scan report for 192.168.0.29
Host is up (0.029s latency).
Not shown: 1 filtered port
Some closed ports may be reported as filtered due to --defeat-rst-ratelimit
PORT STATE SERVICE
22/tcp open ssh
Nmap scan report for 192.168.0.25
Host is up (0.15s latency).
Not shown: 1 filtered port
Some closed ports may be reported as filtered due to --defeat-rst-ratelimit
PORT STATE SERVICE
22/tcp open ssh"
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 SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html