Chapter 5. Controlling Ownership & Permissions
Unix and Unix-like operating systems are multiuser systems in which your files are separate from Jane's files, which are separate from Joe's files, and so on. Any file you create is separate from other users' files and usually cannot be directly accessed by Jane, Joe, or any other user.
Occasionally, though, you will need to share files. For example, you might be collaborating on a project with Jane where sharing files (rather than creating and maintaining separate ones) is essential.
This chapter provides an overview of Unix file permissions and ownership. For many systems, though, only the root user can make ownership changes, so you may have to ask for help from your system administrator to actually do this.