MPE/iX Shell and Utilities Reference Manual, Vol 2

Access Control
This section provides an overview of implementation considerations you should understand when
using access control features as implemented by MPE/iX
Shell and Utilities.
MPE/iX Shell and Utilities fully supports the access permission features defined by the POSIX.1 standard.
MPE/iX supports additional access security features, but in most cases they remain transparent through
MPE/iX Shell and Utilities.
You may, however, need to understand these underlying access security features if you access files or
directories that were not created through MPE/iX Shell and Utilities, or if the security of those files or
directories was modified by
MPE/iX CI commands or system intrinsics.
MPE/iX Access Control Definitions
MPE/iX Shell and Utilities fully supports the POSIX.1 access permissions through the use of the
MPE/iX
access control definition (ACD) facility. Except in cases described below, ACD access control remains
transparent when used through
MPE/iX Shell and Utilities. MPE/iX Shell and Utilities automatically
translates between the POSIX.1 view of access permission and the
MPE/iX view of access permission.
For more information about MPE/iX ACDs, refer to New Features of MPE/iX: Using the Hierarchical
File System (32650-90351).
Mapping Between POSIX.1 and ACD Access Permissions
Table A-1 shows how POSIX.1 file permissions correspond to
MPE/iX ACD access permissions.
POSIX.1 ACD Access Permissions
Read ACD read (R) access
Write ACD write (W) access
Execute ACD execute (X) access
Table A-1: Mapping Between POSIX.1 and ACD File Access Permissions
Table A-2 shows how POSIX.1 directory permissions correspond to MPE/iX ACD access permissions.
POSIX.1 ACD Access Permissions
Read ACD read directory entry (RD) access
Both ACD create directory entry (CD) and
ACD delete directory entry (DD) access
Write
Execute ACD traverse directory entries (TD) access
Table A-2: Mapping Between POSIX.1 and ACD Directory Access Permissions
A-4 MPE/iX Implementation Considerations