Question 5 PLEASE

1. What is the difference between ~grep~ and ~egrep~? What additional symbols are added?

The only difference is the way they interpret the pattern. grep stands for Global Regular Expressions Print. egrep stands for Extended Global Regular Expressions Print.+ ? | are the additional symbols

2. Give an example of something that is easy to match but hard to validate (but not an example used in the lecture).

3. Is this a valid regular expression pattern, ~[a-zA-Z0-9]~? If so, what does it match? 4. Write *two* ~egrep~ commands to look for occurances of "abc" in a file called ~letters.txt~. 5. Modify one of the previous commands to just print how many occurances occured. Use the ~wc~ command to count how many lines there were. 6. What are the two replacement strings for regex? Give an example of both of them.