UNIX

Why are regular expressions useful in Unix? b) What are the grep and egrep commands used for, and what is the difference between them? c) Give the command to search the file usernames.txt for all lines ending with goodbye or later or farewell d) Give regular expressions (such that could be used with grep and egrep) for each of the following: - All lines beginning with the phrase Unix is - All lines that end in either a, b, or c - All lines that contain the word result followed by any three numbers - All lines that contain either 0 or 1 instances of the character x, but no more - All lines that contain a word with 0 or more of the letter a, followed by 1 or more of the letter b, followed by 0 or 1 letter c

Problem 3 (14 points): Answer the following questions about regular expressions a) Why are regular expressions useful in Unix? hat are the grep and egrep commands used for, and what is the difference between them? goodbye' or 'later' or 'farewell each of the following c) Give the command to search the file 'usernames.txt' for all lines ending with d) Give regular expressions (such that could be used with grep and egrep) foir All lines beginning with the phrase 'Unix is All lines that end in either 'a', 'b', or 'c' All lines that contain the word 'result followed by any three numbers All lines that contain either 0 or 1 instances of the character 'x', but no more All lines that contain a word with 0 or more of the letter 'a', followed by 1 or more of the letter 'b', followed by 0 or 1 letter 'c