Tools and packages are located in various places on our systems. E.g. standard Solaris programs can be found under /usr/bin, and the current Studio compiler suite under /opt/studio12.

To be able to access these different tool locations requires configuring the environment of your login shell. This usually means setting the "PATH" variable to include the directories where programs are found.

It is possible to do this explicitly in your shell's startup files. However, over time, what you have in your files will not match newer versions of tools that have been installed and having to make configuration changes is a distraction.

1. usepackage provides you with a command (actually a shell alias/function) called "use" that changes your environment for you.
2. at login the system provides you with a sensible default environment.

usepackage lets you set up your environment with a single command and package name. Example: you are compiling some software that requires Studio 10 instead of the system default, Studio 12:

    $ echo $PATH
    /opt/studio12/SUNWspro/bin: .........

    $ use studio10

    $ echo $PATH
    /opt/studio10/SUNWspro/bin: .........

This has prepended the bin directory for Studio 10 to your PATH (and set the environment for the right man pages too). Your login shell now will invoke the Studio 10 compilers (you can verify this with the command "version").

To make this permanent (for every time you login), add a "use" line to your login shell's startup file, e.g.

    bash: ~/.bash_profile
    csh/tcsh: ~/.login,
    sh/ksh: ~/.profile

(In the /etc/skel directory you'll find the system-wide default files that new accounts receive. There's a comment in each default file with an example "use".)

The system will give you a default set of packages, which can then be extended by your shell's startup files. To see this default and all available packages, run "use -l", e.g.

    $ use -l

    usepackage 1.7, Copyright (C) 1995-2003  Jonathan Hogg

    Available packages are:

       ...

    Available groups are:

      standard-user-settings - sge6, ct6, studio12, x11, blastwave, ccs, system
      chemistry - g03, autodock305

This means you will, automatically and with no effort on your part, be able to use all the standard Solaris programs, various GNU and utility packages, X11 programs, Studio 12 compilers, MPI tools, and Grid Engine for submitting jobs. If you want to add other packages or package groups (e.g. chemistry oriented), just "use" the package name or group.

The default grouping will be updated to track new versions, e.g. when Studio 12 is the released compiler suite, the package "studio12" will become part of "standard-user-settings" instead, and new logins will pick this up automatically.

You can of course ignore all of this, and set your environment by hand as you are used to, if you prefer.

If you need to access the "use" command outside of the login shell (e.g. customizing a package from a shell script) it is possible to do so with a simple "source" command. Please ask HPCVL user support about this.