QUESTION 3 PLEASE 1. What is the difference between ~grep~ and ~egrep~? What add

Question

QUESTION 3 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.

Explanation / Answer

Answer 3:

It is a valid regular expression and matches any one character which is a lower/upper case letter (A to Z) or a digit from 0 to 9

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