Removes all IPs from known_hosts except IPs that start with 192 or have an FQDN

gistfile1.txt

while IFS= read -r line; do
    if [[ $line =~ ^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+[[:space:]] ]]; then
        ip=$(echo "$line" | awk '{print $1}')
        if [[ $ip =~ ^192\. ]]; then
            echo "$line"
        fi
    else
        echo "$line"
    fi
done < ~/.ssh/known_hosts > ~/.ssh/known_hosts.new && mv ~/.ssh/known_hosts.new ~/.ssh/known_hosts