Technical data

Table 2–10: File Ownership Differences
OpenVMS
UNIX
The OpenVMS operating system controls
file ownership and access through a user
identification code (UIC). A UIC is a
32-bit value that consists of a 14-bit group
number, a 16-bit member number, and 2
reserved bits. Each user of the system has a
UIC defined in the SYSUAF file. Access to
objects depends on the relationship between
theUICoftheaccessingprocessandthe
UIC of the object (the file or directory).
OpenVMS controls file access through an
access control list (ACL). You can deny
or grant read, write, execute, delete, and
control access to a user or group of users
whohavetheidentifierspecifiedbythe
ACL. For additional ACL information, refer
to the OpenVMS documentation set.
The NFS protocol does not provide ACL
support. Therefore, the NFS client is
unaware of ACLs that the NFS server
applies to the file. Consequently, the
NFSclientcannotuseanACLtocontrol
file access. Access control is determined
through standard file protections. For more
information, see Chapter 2.
The UNIX operating system controls access
to files with user identification (UID)
and group identification (GID). Tru64
UNIX uses 32-bit UIDs and GIDs. For
compatibility, NFS also recognizes 32–bit
UIDs and GIDs.
2.2.11 File Protections
The OpenVMS and UNIX operating systems use similar file protection schemes, as
shown in Table 2–11.
Table 2–11: Comparison of File Protection
Mechanism
OpenVMS
UNIX
User classifications SYSTEM (S)
OWNE
R(O)
GROUP (G)
WORLD (W)
Class
ification depends on the
relat
ionship between the UIC
of the
accessing process and the
objec
t.
user (u)
--- The user has a
matching UID
grou
p (g)
--- The user has a
mat
ching GID
other (o)
--- Any other user
System category is not used;
system administrators always
have access to UNIX files.
Understanding OpenVMS and UNIX Implementations 2–9