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Understanding Superuser Status
The superuser is a privileged user with unrestricted access to all files and commands. The superuser has the special UID (user ID) 0. The user name for this account is root. Note that the terms root and superuser have the same meaning and are used interchangeably in this book. You must be root to perform many system administration tasks, such as mounting and unmounting file systems, changing ownership or permissions for a file or directory you do not own, backing up and restoring file systems, creating device files, and shutting down the system.
You can become superuser in one of two ways.
When you have superuser privileges, the shell provides a special # (pound sign) prompt to remind you that you have extra access to the system. The system keeps a log that records each time the su command is used and who uses it. You can keep track of who is using the superuser account with the su command by consulting the /var/adm/sulog log file. This log does not track direct root logins.
Become superuser only when it is required, and avoid doing your routine work as superuser. Occasionally, you may need to log out of your user account and log in again as root. When a task in this book requires you to log in as root, you are instructed to do so. You should switch user (su) to root, perform the required tasks, and exit superuser status when the tasks are complete.
Because unauthorized access to root can be a serious security breach, always add a password to the root account. For enhanced security, change the root password frequently.
NOTE. The default shell for root is the Bourne shell. See Chapter 4, "Understanding Shells," for more information on shells.
Becoming Superuser (su)
Become superuser only when you need to perform a task that requires root permissions. Use the following steps to become superuser.
oak% su Password: #
NOTE. If you want to use root's environment variables, type su – and press Return.
Exiting Superuser Status
To exit superuser status, simply type exit and press Return. The shell prompt is redisplayed.
# exit oak%
Logging In as Root
For you to log in as root, ensure that the system is at a login prompt.
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