security

In my last article, I introduced the idea of permissions in the Linux world. Some users can read or write a file, while others can only read the same. A user may also belong to a group and share the permissions of that group which might also involve the ability to execute, or run a file as a program.

Under Linux, access to files and directories is controlled by a system of permissions. Those permissions define who can see a file, whether they can modify it in any way, and in the case of some files, whether the commands within that file (or the file itself) can be executed. By executed, we mean "can we run that program?".