File access permissions
Because the UNIX operating system
provides a multiuser environment,
permissions are assigned to files.
Each user is identified primarily by
a user ID (UID),
and secondarily by a group ID (GID).
Any process started by a user
is associated with
that user's UID and GID.
Within the filesystem,
files have ownership expressed
through a combination of an attached
UID, GID, and access permission flags.
All these are actually specified in the inode,
so that references from several directories
have the same ownership and access restrictions
from all points.
The access permissions are specified by
read, write, and execute permissions for each of:
owner (process UID matches inode UID)
group (process GID matches inode GID)
other (no match)
Note that all applications running on
embedded clients have root permissions.
© 2005 The SCO Group, Inc. All rights reserved.