Permissions are used to prevent the wrong people from doing the wrong things with your files. Including hackers.
Every Unix file has a set of permissions associated with it that specify who is allowed to use that file and in what way.
There are three kinds of permissions:
- A read permission means someone can see what is in the file.
- A write permission means someone can change what is in the file, or even remove it.
- An execute permission means someone can run (execute) a file, if that file contains a program.
- The owner permissions specify what the owner of the file can do.
- For a discussion of group permissions.
- The world permissions specify what anyone can do.