You invoke OYSTER at the UNIX prompt by typing (the actual path may be different on your system):
Provided PV-WAVE (version 6.0 or higher) or IDL (version 5.0 or higher) is installed, the language will start up and read and execute the commands in oyster/oyster.pro. This procedure file will first determine the location of the oyster, atmospheres, and catalogs home directories, then load the compiled procedures in oyster.cpr, set the common blocks and call the procedure setup_oyster to finish the setup. At this point, OYSTER procedures and functions are ready to use at the command line or through invoking the main widget by typing oyster. If you are using remote login to work on the machine with the IDL installation, you should set the DISPLAY environment variable accordingly before you start oyster (e.g. setenv DISPLAY adi.usno.navy.mil:0.0). Use the xhost command before initiating remote login to allow the remote machine to access your display (e.g. xhost +fornax.usno.navy.mil). However, all this is not needed if you use secure shell. Type quit to exit OYSTER.