6 Access Level

In Linux, and many Unix-like file systems, there are three levels of access to each file.

• Owner (u). ``Owner'' means the ``user'' who created the file.
• Group (g). ``Group'' means, of course, ``group''.
• World (o). ``World'' means everyone, the abbreviation o means ``others''.

Each level of access has its own permissions that are independent of the other levels of access. In Linux, it is a convention to first list the permissions of the owner, then permissions of the group, then permissions of ``world''.

Let us consider the following example:

rwxr-xr--

The first three letters, rwx indicates how the owner of the file can access it. In this case, the file can be read from, written to and executed. The next three letters, r-x indicates how the group of the file can access it. r-x means the file is readable and executable. The last three letters, r-- indicates the file is read-only to ``world''.

It is relatively easy to understand the owner of the file. The owner of a file is the user who changed it last. ``World'' is also easy to understand, it simply means ``everyone''. ``Group'', on the other hand, requires some explanation.