Text Modes

u

The file's owner.

g

The group associated with the file or directory.

o

Other users (users that are not the owner, and not in the group).

a

All (owner, group and others).

=

Assigns the permissions Example: "a=rw" sets read and write permissions and disables execution for all.

-

Removes a specific permission. Example: "a-x" revokes execution permission from all users without changing read and write permissions.

+

Adds a specific permission. Example: "a+x" grants execution permission to all users without changing read and write permissions.

r

Read permission

w

Write permission

x

Execute permission