File and Directory Ownership

Traditional UNIX file permissions can assign ownership to three classes of users:

• user – The file or directory owner, who is usually the user who created the file. The owner of a file can decide who has the right to read the file, to write to the file (make changes to it), or, if the file is a command, to execute the file.

• group – Members of a group of users.

• others – All other users who are not the file owner and are not members of the group.

The owner of the file can usually assign or modify file permissions. Additionally, the root account can change a file's ownership. To override system policy, see Enabling Users to Change the Ownership of Their Own Files.

A file can be one of seven types. Each type is displayed by a symbol:

- (Minus symbol)

Text or program

b

Block special file

c

Character special file

d

Directory

l

Symbolic link

s

Socket

D

Door

P

Named pipe (FIFO)