You can use the question mark to display a list of commands available in the prompt you are in:
Router#? Exec commands: <1-99> Session number to resume auto Exec level Automation clear Reset functions clock Manage the system clock configure Enter configuration mode connect Open a terminal connection copy Copy from one file to another debug Debugging functions (see also 'undebug') delete Delete a file dir List files on a filesystem disable Turn off privileged commands disconnect Disconnect an existing network connection enable Turn on privileged commands erase Erase a filesystem exit Exit from the EXEC logout Exit from the EXEC mkdir Create new directory more Display the contents of a file no Disable debugging informations ping Send echo messages reload Halt and perform a cold restart --More--
If the output spans more than one page, press the spacebar to display the following page of commands, or press Enter to go one command at a time. To quit the output, press q.
To display only commands that start with a particular character or a string of characters, type the letters and then press the question mark:
Router#de? debug delete
In the picture above you can see that we’ve displayed all commands that start with de.
If the command is more than one word long, you can use the question mark to display the next command in a string:
Router#debug ? aaa AAA Authentication, Authorization and Accounting custom-queue Custom output queueing eigrp EIGRP Protocol information frame-relay Frame Relay ip IP information ipv6 IPv6 information ntp NTP information ppp PPP (Point to Point Protocol) information standby Hot Standby Router Protocol (HSRP) Router#debug eigrp ? fsm EIGRP Dual Finite State Machine events/actions packets EIGRP packets
In the picture above you can see that we’ve displayed all commands that can follow the command debug. We then displayed all commands that can follow the commands debug eigrp.
You can also autocomplete a command. Just type the first few characters and press Tab. If there is only a single match, IOS will complete the command.
You don’t have to type an entire word to finish a command. Just can type just the first letter or a couple of letters, and if there is only a single match, IOS will understand what are you trying to accomplish. For example, you can type sh ip int b instead of the longer version, show ip interface brief:
Router#sh ip int b Interface IP-Address OK? Method Status Protocol GigabitEthernet0/0 unassigned YES NVRAM administratively down down GigabitEthernet0/1 unassigned YES NVRAM administratively down down GigabitEthernet0/2 192.168.0.1 YES manual up down Vlan1 unassigned YES NVRAM administratively down down
Note that we were able to execute the command above because each set of characters had only one match in the list of commands. If we’ve typed sh ip in b instead, IOS would not have understood our intention:
Router#sh ip in b % Ambiguous command: "sh ip in b"
The % Ambiguous command: “show ip in b” message was displayed because the third keyword, in, has more than one meaning (inspect or interface).
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