Linux Tools

Question 1

How would you replace every occurrence using 'sed' of the substring 'hello' by the substring 'goodbye' in a file named "mywords.txt" and save the output in "mynewwords.txt"? Give exact syntax.

Question 2

How would you display a list of users currently logged into the system, such that every username (and just the username) appears only once? Give exact syntax.

Question 3

How would you display all files in current directory that are newer than "file.txt"? Give exact syntax.