Linux assigns default permissions when a file or directory is first created, but these permissions may not provide the security you need. To change permissions on files and directories the owner can execute the chmod command.

Chmod can be used to change permissions in one of two modes:

  • Symbolic mode is easier to read because it uses symbols to change the state of the permission bits (you will see this later in the chapter)
  • Absolute (or octal) mode is a little harder to read because it uses numbers to change permissions but it can be faster to use because it requires less typing.

On the next page we will see how to change permissions using chmod in symbolic mode.

Note: Only the owner of the file or the Superuser can change a file's permissions.