We can find out which commands we are allowed to be used in the IOS system by using ?.
For example, a question mark entered on the command line in non-privileged mode:
Router>? Exec commands: access-enable Create a temporary Access-List entry access-profile Apply user-profile to interface clear Reset functions connect Open a terminal connection disable Turn off privileged commands disconnect Disconnect an existing network connection enable Turn on privileged commands exit Exit from the EXEC help Description of the interactive help system lock Lock the terminal login Log in as a particular user logout Exit from the EXEC —More—
The question mark command can also be used to obtain a list of commands that begin with a particular character sequence. Just type in those characters followed immediately by the question mark.
For example:
Router>p? *p=ping pad ping ppp
Alternatively, we can enter a command followed by a question mark without the parameters and the IOS...