Datasheet

Caution
Do not use telnet over a network on which third parties can eaves-
drop. Particularly on the Internet, use encrypted transfer methods,
such as ssh, to avoid the risk of malicious misuse of a password
(see the man page for ssh).
Caution
Miscellaneous
passwd [option(s)] [username] Users may change their own passwords
at any time using this command. The administrator root can use the com-
mand to change the password of any user on the system.
su [option(s)] [username] The su command makes it possible to log in
under a different user name from a running session. When using the com-
mand without specifying a user name, you will be prompted for the root
password. Specify a user name and the corresponding password to use
the environment of the respective user. The password is not required from
root, as root is authorized to assume the identity of any user.
halt [option(s)] To avoid loss of data, you should always use this program
to shut down your system.
reboot [option(s)] Does the same as halt except the system performs an
immediate reboot.
clear This command cleans up the visible area of the console. It has no options.
21.4 The vi Editor
Operating the vi editor takes some practice. For many, it is the preferred editor,
partly because it is available on any UNIX-like operating system and is included
in default Linux installations. Also, if nothing else works, vi will. The short in-
structions that follow should enable you to edit various configuration files and
other types of files with vi.
vi provides three operating modes. In command mode keys are interpreted as
command elements. Insert mode interprets all keys as text entries. Last line mode
is used for more complex commands, which are entered in the last line.
278 21.4. The vi Editor