Cisco Networking: Command Options
The Cisco networking Internetwork Operating System (IOS) has a great context-sensitive Help function, which means the IOS can help you find the specific item you are currently working with.
To start using Help, you need to type a command in the CLI. After you type one command, you can ask the IOS for help with possible options for that command. After you type your selected command, type a space and a question mark to get a list of options for that command. For example, running the copy command with the question mark results in the following:
Router#copy ? /erase Erase destination file system. /noverify Don't verify image signature before reload. /verify Verify image signature before reload. cns: Copy from cns: file system flash: Copy from flash: file system ftp: Copy from ftp: file system http: Copy from http: file system https: Copy from https: file system null: Copy from null: file system nvram: Copy from nvram: file system pram: Copy from pram: file system rcp: Copy from rcp: file system running-config Copy from current system configuration scp: Copy from scp: file system startup-config Copy from startup configuration system: Copy from system: file system tftp: Copy from tftp: file system
In fact, if you have not typed anything on the CLI, you can still type the question mark to get a list of all the available commands that you can use from your current mode. This is a very long list, so if you start with the first few letters of the command, you will greatly reduce the size of the list.