Using Command Line Online Help

When entering command lines, you can enter a question mark (?) at any time to obtain online help. You can choose to obtain full help or partial help.

Full Help

When entering a command, you can use the full help function to obtain keywords and parameters for the command. Use any of the following methods to obtain full help from a command line.

Enter a question mark (?) in any command view to obtain all the commands and their simple descriptions. For example:

<HUAWEI> ?
User view commands:
  backup         Backup electronic elabel
  cd             Change current directory
  check          Check information
  clear          Clear information
  clock          Specify the system clock
  compare        Compare function
...

Enter some keywords of a command and a question mark (?) separated by a space. All keywords associated with this command, as well as simple descriptions, are displayed. For example:
```
<HUAWEI> system-view
[HUAWEI] user-interface vty 0 4
[HUAWEI-ui-vty0-4] authentication-mode ?
  aaa       AAA authentication, and this authentication mode is recommended
  none      Login without checking
  password  Authentication through the password of a user terminal interface

[HUAWEI-ui-vty0-4] authentication-mode aaa ?
  <cr>

[HUAWEI-ui-vty0-4] authentication-mode aaa
```
- "aaa" and "password" are keywords. "AAA authentication" and "Authentication through the password of a user terminal interface" describe the keywords respectively.
- <cr> indicates that there is no keyword or parameter in this position. You can press Enter to run this command.
Enter some keywords of a command and a question mark (?) separated by a space. All parameters associated with this keyword, as well as simple descriptions, are listed. For example:
```
<HUAWEI> system-view
[HUAWEI] ftp timeout ?
  INTEGER<1-35791>  The value of FTP timeout, the default value is 30 minutes
[HUAWEI] ftp timeout 35 ?
  <cr>

[HUAWEI] ftp timeout 35
```
"INTEGER<1-35791>" describes the value range of the parameter. "The value of FTP timeout, the default value is 30 minutes" briefly describes the function of this parameter.

Partial Help

If you enter only the first or first several characters of a command keyword, partial help provides keywords that begin with this character or character string. Use any of the following methods to obtain partial help from a command line.

Enter a character string followed directly by a question mark (?) to display all keywords that begin with this character string. For example:
```
<HUAWEI> d?
  debugging                               delete
  dir                                     display
<HUAWEI> d
```
Enter a command and a string followed directly by a question mark (?) to display all the keywords that begin with this string. For example:
```
<HUAWEI> display b?
  bpdu                                    bridge
  buffer
```
Enter the first several letters of a keyword in a command and press Tab to display a complete keyword. The first several letters, however, must uniquely identify the keyword. If they do not identify a specific keyword, press Tab continuously to display different keywords and you can select one as required.

The command output obtained through the online help function is used for reference only.