ifconfig - configure a network interface ip - show / manipulate routing, network devices, interfaces and tunnels netstat - Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships ping - send ICMP ECHO_REQUEST to network hosts traceroute, tracepath, tracepath6 - traces path to a network host discovering MTU along this path host - DNS lookup utility nslookup - query Internet name servers interactively dig - DNS lookup utility
if (( $variable < 0 )) then echo "too low" elif (( $variable <= 10 )) then echo "variable is in range 0-10" elif (( $variable <= 20 )) then echo "variable is in range 11-20" else echo "variable is larger than 20"
Ping sends an echo request to a server, if the server responds then you and the server are online.
Traceroute shows the route taken to the server.
Class D is rarely used
A Class A private address is 10.0.0.0/8 and cannot be accessed from the internet
B is /16
C is /8
127.0.0.1 is the loopback address, it sends packets to localhost, the computer that send it