Stella, Welcome to Javaranch! We do have a Linux/UNIX forum, so if this gets away from Oracle and too much into scripting, I'll move it there.
A korn shell script is basically just a sequence of commands. So you need to figure out how to run those commands at the command line (rather than from within Oracle.) I don't have my Oracle docs with me, but I imagine it is in there.
I would advise trying the commands one at a time at the command line. Once you have each one working, add it to a file. When you are done with the third one, you have a script! Just make sure the script has execute permission and you're done.