Privilege (computer science)

A privelege in a computer system is a permission to perform an action. Examples of various priveleges include the ability to create a file in a directory, or to read or delete a file, access a device, or have read or write permission to a socket for communicating over the Internet.

Priveleges can either be automatic, granted, or applied for.

An automatic privelege exists when there is no requirement to have permission to peform an action. For example, on systems where people are required to log into a system to use it, logging out will not require a privelege. Systems that do not implement file protection - such as MSDOS - essentially give unlimited privelege to perforn any action on a file.

A granted privelege exists as a result of presenting some credential to the privelege granting authority. This is usually accomplished by logging on to a system with a username and password, and if the username and password supplied are correct, the user is granted additional priveleges.

A privelege is applied for by either an executed program issuing a request for advanced priveleges, or by running some program to apply for the additional priveleges. An example of a user applying for additional priveleges is provided by the sudo command to run a command as the root user, or by the Kerberos authentication system.