Bassi UNIX Environment

IBM's brand of UNIX is known as AIX. AIX does not use the module approach to environment management for system software such as compilers and run-time libraries. However, third-party and public domain software installed and managed by NERSC's User Services Group (USG) are accessible through modules. Most third-party software is not in your default command search path; you must load the corresponding module to use the software.

Your AIX initialization files in your home directory (dot-files) have been configured for maximum flexibility and ease of maintenance, both for you and the NERSC staff. A long listing of your dot-files should look similar to this:

% ls -la
total 1152
drwxrwxr-x   2 user   aaa    8192 Sep 14 18:58 ./
drwxrwxr-x  32 bin    aaa    8192 Oct 05 12:33 ../
lrwxrwxrwx   1 user   aaa      26 Sep 14 18:58 .bash_profile@ -> /usr/common/usg/etc/.bash_profile
-r-xr-xr-x   1 user   aaa      74 Sep 10 11:01 .bash_profile.ext
lrwxrwxrwx   1 user   aaa      26 Sep 14 18:58 .bashrc@ -> /usr/common/usg/etc/.bashrc
-r-xr-xr-x   1 user   aaa      74 Sep 10 11:01 .bashrc.ext
lrwxrwxrwx   1 user   aaa      26 Sep 14 18:58 .cshrc@ -> /usr/common/usg/etc/.cshrc
-r-xr-xr-x   1 user   aaa      74 Sep 10 11:01 .cshrc.ext
lrwxrwxrwx   1 user   aaa      27 Sep 14 18:58 .kshrc@ -> /usr/common/usg/etc/.kshrc
-r-xr-xr-x   1 user   aaa      83 Sep 10 11:02 .kshrc.ext
lrwxrwxrwx   1 user   aaa      26 Sep 14 18:58 .login@ -> /usr/common/usg/etc/.login
-r-xr-xr-x   1 user   aaa     183 Oct 01 13:08 .login.ext
lrwxrwxrwx   1 user   aaa      28 Sep 14 18:58 .profile@ -> /usr/common/usg/etc/.profile
-r-xr-xr-x   1 user   aaa     194 Oct 01 13:08 .profile.ext 
lrwxrwxrwx   1 user   aaa      26 Sep 14 18:58 .tcshrc@ -> /usr/common/usg/etc/.tcshrc
-r-xr-xr-x   1 user   aaa      74 Sep 10 11:01 .tcshrc.ext

The files .cshrc, .login, .profile, .bash_profile, .bashrc, and .kshrc are read-only links. Please do not delete them. You should make all your individual customizations in the files named *.ext. These .ext files are sourced by the corresponding dot-files.

% module initadd module_name

This will store the module information in $HOME/.modules, which is common to all shells. If your home directory does not contain these links and .ext files, run the following command to re-create them. The following command will overwrite all your current dot files, so first rename any that you want to keep.

% /usr/common/usg/bin/fixdots

Shells

Also see Shells and Scripting.

                /usr/bin/sh
                /usr/bin/bsh
                /usr/bin/csh
                /usr/bin/ksh
                /usr/bin/tcsh
                /usr/bin/bash

The shells tcsh and bash are not supported by IBM, so use with some caution. Please do not use tcsh and bash to parse batch scripts as they have been known to cause occasional problems. Always include the following in your LoadLeveler scripts:

#@shell = /usr/bin/csh

where csh can be replaced by sh or ksh.

Shell Initialization Files

Upon startup, shells execute commands contained in what are commonly referred to as "dot files." Each shell reads different files. This can be very confusing, because there is no standard and shells can be configured to do things in many different ways, and different versions of shells have different defaults. Each operating system and site implements different sequences. Interactive and non-interactive shells behave differently, as do sessions started interactively at terminals and sessions started by issuing remote commands via ssh or rsh. There may be other rules for subshells. Your choice of login shell also has an effect when you spawn subshells or execute scripts.

NERSC has tried to simplify things so software will "work" as you expect in varied environments: interactive session, batch jobs, remote queries, in makefiles, etc. This sometimes leads to tortured execution paths through startup files and surprises when a shell acts differently than you are used to at another site.

Parallel Environment

See Running Programs for a discussion of the parallel operating environment on Bassi.