(source http://www.stokely.com/stokely/lighter.side/whos.on.what.html,
Author Unknown)

A Customer calls a UNIX consultant with a question: 

Customer: What is the command that will tell me the revision code of a program ?

UNIX Consultant: Yes, that's correct. 

Customer: No, what is it ? 

UNIX Consultant: Yes. 

Customer: So, which is the one ? 

UNIX Consultant: No. 'which' is used to find the program. 

Customer: Stop this. Who are you ? 

UNIX Consultant: Use 'who am i' not 'who r yoo'. You can also 'finger yoo'
to get information about yoo'. 

Customer: All I want to know is what finds the revision code ? 

UNIX Consultant: Use 'what'. 

Customer: That's what I am trying to find out. Isn't that true ? 

UNIX Consultant: No. 'true' gives you 0. 

Customer: Which one ? 

UNIX Consultant: 'true' gives you 0. 'which programname' 

Customer: Let's get back to my problem. What program? How do I find it? 

UNIX Consultant: Type 'find / -name it -print' to find 'it'. Type 'what
program' to get the revision code. 

Customer: I want to find the revision code. 

UNIX Consultant: You can't 'find revisioncode', you must use 'what program'. 

Customer: Which command will do what I need? 

UNIX Consultant: No. 'which command' will find 'command'. 

Customer: I think I understand. Let me write that. 

UNIX Consultant: You can 'write that' only if 'that' is a user on your system. 

Customer: Write what? 

UNIX Consultant: No. 'write that'. 'what program'. 

Customer: Cut that out! 

UNIX Consultant: Yes. those are valid files for 'cut'. Don't forget the

Customer: Do you always do this ? 

UNIX Consultant: 'du' will give you disk usage. 

Customer: HELP! 

UNIX Consultant: 'help' is only used for Source Code Control System (SCCS). 

Customer: You make me angry. 

UNIX Consultant: No, I don't 'make me' angry but I did 'make programname'
when I was upset once. 

Customer: I don't want to make trouble, so no more. 

UNIX Consultant: No 'more'? 'which' will help you find 'more'. Every system
has 'more'. 

Customer: Nice help! I'm confused more now! 

UNIX Consultant: Understand that since 'help' is such a small program, it is
better not to 'nice help'. and 'more now' is not allowed but 'at now' is.
Unless of course
'now' is a file name. 

Customer: This is almost as confusing as my PC. 

UNIX Consultant: I didn't know you needed help with 'pc'. Let me get you to
the Pascal compiler team.