Shell Programming and Scripting

I have these questions for my unix class that I can't figure out because I missed a couple of days. They are for a quiz we took last week so by answering the questions you are not bettering my grade or doing my homework. I just want to understand was the answers. My teacher is really bad at explaining things.


1. Matcha line containing the assignment of a value to a legal shell variable in grep.

2. Match a word containing a repeating sequence of characters, with one or more characters in between, in grep, e.g., match "abcxyabc" or "xax", but not "abcd" or "aa".

3. Exchange the second and third words on a line with at least 4 words in sed, leaving the rest unchanged, e.g., "hi there joe kool" becomes "hi joe there kool", but "hi there joe" is unchanged.

4. Match lines containing one or more letters immediately followed by one or more digits in grep, e.g., match "abc123" or "a7" but not "az-12".

5. Match lines containing a repeating sequence of letters followed at any distance by one or more digits in grep, e.g., match "axax123" or "aaxyz7" but not "az12" in grep.

Don't open another thread. Neo has already explained the rules to you.