Special-purpose and limited accounts : User Administration

Create and manage special-purpose  and limited accounts : User Administration



Create and manage special-purpose  and limited accounts 


There are actually a lot of user accounts listed in the /etc/passwd file on any Linux system, even
if you’ve only created one or two accounts. All of the other user accounts are systemuser accounts.



Three sample system user accounts are shown here:


sshd:x:495:494:SSH daemon:/var/lib/sshd:/bin/false
uucp:x:10:14:Unix-to-Unix CoPy system:/etc/uucp:/bin/bash
wwwrun:x:30:8:WWW daemon apache:/var/lib/wwwrun:/bin/false



System user accounts aren’t used for login. Instead, they are used by services running on the
system. When one of these services needs to do something in the Linux file system, it does so as
its associated user account from /etc/passwd.


Notice that the system user accounts have a much lower UID number as compared to standard user accounts.

UIDs between 0 and 499 are typically reserved for system accounts, depending on the distribution.


For example, suppose I’ve logged in to the ftp service on my Linux system as an anonymous user and uploaded a file. This file needs to be written to the ftp service’s default directory in the file system. When it writes, it does so as the ftp user.









LX0-104 Exam Objectives (K)