The Top Ten Concepts For Beginners to Linux - Number 3, Users
Unlike Windows, Linux users must have an account. This account is accorded permission to do things such as read and write files and execute programs. For ease in account management, accounts are combined into groups. Users belonging to a group may be assigned additional permissions that smooth the process of accessing common files. Let's take a closer look at how Linux handles these users. Another article will examine permissions and groups.
Linux provides two categories of users, ordinary users essentially restricted to working with files of their own creation, and the superuser, or root, who administers the system and is allowed to do almost anything. The real situation is of course somewhat more complex. For example, ordinary users may be accorded restricted access to additional files deemed to be of interest to everyone. The superuser may assign selected privileges to deputies reducing an otherwise crushing workload.
The root user is the only one authorized to run the adduser or the more complicated useradd command. If you have downloaded Damn Small Linux you can test these commands on your Windows computer. In response to the adduser command Linux requests the user name, the password, and then a few optional fields that may be skipped. An organization with many users has or should have a policy for composing user names.
The password is a key element in protecting the computer's security. We could easily write an article discussing the password and password selection. Remember that Linux distinguishes between lower-case and upper-case letters. If you're a new user you may start with easily remembered passwords. But protecting your account and account information depends on your unguessable passwords.
As Linux creates your account it creates a directory whose name is easy to remember. If your account name is lucy then your working directory is /home/lucy . I'm leaving it up to you to find out the location of lucy's working directory when she uses Windows systems.
Damn Small Linux shares an interesting feature with many other Linux systems. The system administrator can provide new users with copies of some directories and folders by placing them in the /etc/skel directory before launching the adduser command.
How is the system administrator supposed to handle creating dozens, hundreds, or even thousands of new users, for example at the beginning of the semester? He or she won't have the time to undertake this backbreaking task. And there is no way that the root password should be revealed to the employee who is assigned this task. The answer is simple: write a program to create these new accounts. This program can even spiff up the account creation interface and perhaps grab some necessary information from sources such as the student registration file.
Of course we don't want to create users without the possibility of removing them. The live process is fairly complicated and includes removing the user's password from the /etc/passwd directory, removing all files from the user directory, and other activities such as making backups of essential information. The next article discusses the related concepts of permissions and groups.
About the Author
Levi Reiss has authored or co-authored ten books on computers and the Internet. He loves the occasional glass of wine as exemplified by his wine websites. He teaches Linux and Windows operating systems plus other computer courses at an Ontario French-language community college. Visit his new website http://www.linux4windows.com which teaches you how to download and run Damn Small Linux on Windows computers, even if they are "obsolete."
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