| 3.3 | Important Cisco IOS Features | ||
| 3.3.2 | Using the help feature |
|
The help command on a Cisco IOS command-based switch works the same as that on a router. On a switch, you access help by entering ? on a command line. The switch then prompts you with all possible choices for the next parameter. If you type in the next parameter and type ? again, the switch displays the next set of command-line choices. In fact, the switch displays help on a parameter-by-parameter basis. Additionally, when the switch displays help options, it also ends by displaying the portion of the command that you entered so far. This enables you to continue to append commands to the line without needing to reenter the previous portion of the command. The help system on a set
command-based switch functions differently from the router. You access help in the same manner as you do in a router, but the
results differ. For example, where a router prompts you for the next
parameter, the Catalyst switch displays the entire usage options for
the command. Figure On the other hand, if you have enough
of the command on the line that the Catalyst switch recognizes what
command you intend to implement, it displays the options for that
command. This time, in Figure Notice that when the console displays
help, it returns the command line with a blank line. The command
string you entered so far is not displayed for you as it is on a
router. You can now use command recall. Suppose you want to
disable the logical interface, sc0. So you want to enter the command
set int sc0 down.
You decide to use command recall and complete the command. What happens if you type !!
sc0 down ? You see the
command usage screen again, without the console changing state to
down. This happens because the command recall executes the previous
statement that was set int ?
with the help question mark and your appended parameters. When you
add the additional parameters, the switch interprets the string as set
int ? sc0 down, sees the
question mark, and displays help.
|