? / <prefix>? / <command> ?
Context help, exactly like a real device: '?' alone lists every command in this mode; 'sh?' (glued) lists the commands that start with sh; 'ip ?' (spaced) lists the words that may come next, one per line. A complete command prints '<cr>'; nothing matching prints '% Unrecognized command'.
Example
R1(config)# ip ?
route
default-gateway
name-server
domain-name
...
R1# sh?
showThe same tables drive Tab completion, so anything '?' lists can also be completed with Tab. Help requests are never added to the command history (arrow-up skips them).
Don't just read it — type ? / <prefix>? / <command> ? in a real network simulator in your browser and watch it take effect. No install, no account needed to start.
Frequently asked
What does the "? / <prefix>? / <command> ?" command do?
Context help, exactly like a real device: '?' alone lists every command in this mode; 'sh?' (glued) lists the commands that start with sh; 'ip ?' (spaced) lists the words that may come next, one per line. A complete command prints '<cr>'; nothing matching prints '% Unrecognized command'.
What's the common gotcha with "? / <prefix>? / <command> ?"?
The same tables drive Tab completion, so anything '?' lists can also be completed with Tab. Help requests are never added to the command history (arrow-up skips them).
Example of "? / <prefix>? / <command> ?"
R1(config)# ip ? route default-gateway name-server domain-name ... R1# sh? show