Why Do We Need Permissions?

If a computer is used only by a single user or is used only for something trivial, such as playing games, then there would probably be no real need to have permissions associated with files. However, computers in the workplace tend to be shared by many users, often simultaneously as in the case of Solaris, and also store sensitive information. Also, they are very likely to be attached to a network of some kind.

This means that if we don't do something to stop prying eyes from looking into our files, sooner or later the wrong people will see something they shouldn't or, possibly worse, delete something they shouldn't (but of course, we all make regular backups—don't we!).

Files are protected under Solaris by being given an owner, a group, and a set of permissions. The permissions say what the owner may do to the file, what users in the same group as the files may do, and what all other users may do.