The question mark. It can be used in different contexts, for example:
?
(list all commands that make sense in the current context)
s?
(list all commands that start with s)
show ?
(list what options you have as the second word after the SHOW command, for example, show ip, show running-config, etc.)
The Cisco IOS commands allow the user to enter partial Cisco IOS commands. If you start to type in a command it can recognize it and finish the command for you.
Cisco IOS uses a command line interface (CLI) for inputting commands when configuring Cisco Routers
Cisco IOS uses a command line interface (CLI) for inputting commands when configuring Cisco Routers
show interface status
Divide and conquer
show?
config tftp run
show ip eigrp neighborsw
debug all
flash, NVRAM, TFTP server
Router(config-if)#no frame-relay lmi-type cisco
The Flash memory stores the Cisco IOS image.