w6u6f - it would pay to keep in mind that this forum doesn't do homework for you. We'll help if you have genuine questions but putting a question like this in the forum is likely to get one of three responses......

1. Do your own homework.
2. Read a book.
3. Visit the man page.

So now you know.

But I'll be nice and give you a hint ..... keep in mind that an environment variable can be absolutely anything that you may have a use for. It's really just a place where all your variables within the current shell are stored. Use the man page for each separate variable - some will be generic type ones that will give you a good explanation....others will be customised i.e. logname and will not appear there at all.

Use 'man -k your_word_here'.

This will let you search the man pages for keywords as oppsed to 'man your_word_here' which will search only for that specific command name.

And of course - point 1,2 and 3 above for 'env' and 'set'

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Pete