ABSTRACT Unix is a multifunctional platform capable of handling several users accessing the same applications and files at once. It accomplishes this by setting up a permissions hierarchy and assigning users into groups. As multifunctional as it is, several problems still exist. For one, it has a command line interface. There is no graphical user interface. Second, privilege changes are made either one by one or all at once. Anything else would need to be scripted.

Programmers originally built the Unix operating system for other programmers to use. It is an extensible operating system, meaning it allows programmers to extend and change it to do anything they need it to. Essentially, it is built to multitask. It allows multiple users to use the same app or multiple users access to the same file. Although the computer cannot process all the requests at once, it does prioritize the requests to keep things orderly. If multiple people need access to one file, this is commonly done by placing the users into groups, and assigning the groups and users various levels of permission access. There is a hierarchy where groups are on top and access control lists are underneath. The groups are owner class, group class, and other class. The other privileges are read, write, and execute. When a user creates a file, they are automatically made the owner. They can grant others into the group class and other class. Directory lists have 10 spaces or bits on the left hand side. The first space on the left is either a ‘-‘ for file, or a ‘D’ for directory. Stallings (2012) stated,“ Nine of the protection bits specify read (r), write (w), and execute (x) permission for the owner of the file, other members of the group to which this file belongs, and all other users” (p.558). The first three are for owner, next three are for group and last three are for other. Privileges also can be displayed as numerical. Four (4) for read, two (2) for write, and one (1) for execute. The numerical value ranges from 0-7 for each, depending on which privilege(s) each person has. For example, if a file has privileges of 777, this means that the owner, group, and other class have read, write, and execution rights. If a file has 744, the owner has full privileges while all other classes have read rights. The CHMOD command changes privileges with the numerical value or with ‘+r’, ‘+w’, or ‘+x’. There is debate among professionals regarding the effectiveness of the file protection in Unix. The Unix system has to have group members assigned to groups, which requires high administrative overhead. Another option is to have a role-based permissions policy instead of group based. This means users will have permissions based on the needs of an individual’s job. A manager could be part of the administrative group but may not have the need to change server scripts. A network administrator could have access into the network and server settings and controls but would not be able to change personnel files. Another challenge is permission changes in Unix are either universally or done one at a time. Changes are not easily done a few at a time. Another issue is if a user tries to list the contents of a directory but does not have execution rights, the operating system will say they do not have permission. If a user wants look at a file, he or she will need reading rights. One last option is to compartmentalize each file and specify who can read, write or execute at any given time. Unix file systems are made for speed but are not user friendly. They multitask very well and can be changed for any purpose a programmer desires. A Unix system is suitable for allowing several users to use any single application or access to single files. The file permission structure is not perfect but it permits for specific control over files and directories.

Works Cited Stallings, W. (2012). Operating Systems: Internals and Design Principles (7th ed.). New York, New York: Prentice Hall.