Installation guide

• The shell determines whether the argument you specify to the built-in
cd command is a subdirectory of any of the directories specified in the
definition of the CDPATH environment variable. If the shell finds a
subdirectory that matches the argument you specify, it changes your
current directory to that subdirectory. The ULTRIX sh shell does not
have this feature.
• The default search path for the DIGITAL UNIX sh shell is /usr/bin.
On the ULTRIX system, the default search path is :/bin:/usr/bin.
On the DIGITAL UNIX system, /bin is a link to /usr/bin; you do not
need to add /bin to the definition of your DIGITAL UNIX PATH
environment variable.
• The Bourne shell on ULTRIX has one variant of the shell command,
set − , that does not exist on DIGITAL UNIX systems.
• The DIGITAL UNIX Bourne shell contains a built-in echo command.
The ULTRIX Bourne shell does not contain an echo command.
These differences might affect the portability of your sh shell scripts. For
information about porting sh shell scripts, see Section 3.2.
The DIGITAL UNIX Bourne shell (sh) is almost identical to the ULTRIX
sh5 shell; however, its name is different, and there are a few other minor
differences. The difference in name does not affect how you use the Bourne
shell interactively; however, it might affect the portability of your sh5 shell
scripts. Other differences are very minor but can cause subtle failures of
ported scripts. For information about porting sh5 shell scripts, see
Section 3.2.
2.5 Differences in Security Features
Like the ULTRIX operating system, the DIGITAL UNIX system includes
features that allow you to control access to your account, files, and
workstation. For information on using the DIGITAL UNIX security
features, see the Security manual.
The DIGITAL UNIX system omits the following security features that are
found on ULTRIX systems: trusted path, audit, and enhanced identification
and authentication features (including the shadow password file). For
example, the DIGITAL UNIX system does not support the equivalent of the
ULTRIX authenticate_user programming interface. Additionally, a
DIGITAL UNIX system’s system administrator cannot define a Secure
Attention Key that you press before you log in to the system.
Overview of the DIGITAL UNIX User Environment 2–9