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CLI Help Features

If you printed the Cisco IOS Command Reference documents, you would end up with a
stack of paper several feet tall. No one should expect to memorize all the commands—and
no one does. You can use several very easy, convenient tools to help remember commands
and save time typing. As you progress through your Cisco certifications, the exams will
cover progressively more commands. However, you should know the methods of getting
command help.

Table 6-2 summarizes command-recall help options available at the CLI. Note that, in the
first column, command represents any command. Likewise, parm represents a command’s
parameter. For example, the third row lists command ?, which means that commands such
as show ? and copy ? would list help for the show and copy commands, respectively.

Table 6-2 Cisco IOS Software Command Help
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When you enter the ?, the Cisco IOS CLI reacts immediately; that is, you don’t need to
press the Enter key or any other keys. The device running Cisco IOS also redisplays what
you entered before the ? to save you some keystrokes. If you press Enter immediately after
the ?, Cisco IOS tries to execute the command with only the parameters you have entered
so far.

The information supplied by using help depends on the CLI mode. For example, when
? is entered in user mode, the commands allowed in user mode are displayed, but commands
available only in enable mode (not in user mode) are not displayed. Also, help is
available in configuration mode, which is the mode used to configure the switch. In fact,
configuration mode has many different subconfiguration modes, as explained in the section
“Configuration Submodes and Contexts,” later in this chapter. So, you can get help for the
commands available in each configuration submode as well. (Note that this might be a good
time to use the free NetSim Lite product on the DVD—open any lab, use the question
mark, and try some commands.)

Cisco IOS stores the commands that you enter in a history buffer, storing ten commands
by default. The CLI allows you to move backward and forward in the historical list of commands
and then edit the command before reissuing it. These key sequences can help you
use the CLI more quickly on the exams. Table 6-3 lists the commands used to manipulate
previously entered commands .

Table 6-3 Key Sequences for Command Edit and Recall
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