User Profile

each file has
associated with it eleven bits of protection information together
with a user identification number and a usergroup identification number (UID
and GID). Nine of the protection bits are used to specify independently
permission to read, to write, and to execute the file to the user himself,
to members of the user's group, and to all other users. Each process
generated by or for a user has associated with it an effective UID and
a real UID, and an effective and real GID. When an attempt is made to access
the file for reading, writing, or execution, the user process's effective
UID is compared against the file's UID; if a match is obtained, access is
granted provided the read, write, or execute bit respectively for the user
himself is present. If the UID for the file and for the process fail to
match, but the GID's do match, the group bits are used! Get it !?
..sure you did.

Friends (9):

Friend of (6):