CISCO IOS in a Nutshell

show Commands

As you work with IOS, you’ll become intimately familiar with the show commands. They are among the most useful commands you will ever use; they allow you to view just about any settings within the router. Issuing the command show ? produces output like this:

Router>show ?
  clock     Display the system clock
  history   Display the session command history
  hosts     IP domain-name, lookup style, nameservers, and host table
  sessions  Information about Telnet connections
  snmp      snmp statistics
  terminal  Display terminal configuration parameters
  users     Display information about terminal lines
  version   System hardware and software status

The show command has many different subcommands. However, notice that we are in user mode. In privileged mode, the show command has a lot more subcommands, which would take up a few pages if we listed them here. The important thing to remember is that show commands often have more than one keyword. For example, the command show ip route works by itself, but there are also many other options that can be applied to it. For example:

router#show ip route ? Hostname or A.B.C.D Network to display information about or hostname bgp Border Gateway Protocol (BGP) connected Connected egp Exterior Gateway Protocol (EGP) eigrp Enhanced Interior Gateway Routing Protocol (EIGRP) igrp Interior Gateway Routing Protocol (IGRP) isis ISO IS-IS odr On Demand stub Routes ospf Open Shortest Path First (OSPF) rip Routing Information Protocol (RIP) static Static routes summary Summary ...