Using sed For help using sed, you may find the tutorial http://www.grymoire.com/Unix/Sed.html useful a) Write a one-line sed command that will replace all multiple spaces in a file called names. txt (this iS an arbitrary file that you may create yourself) by only one space b) Consider the following file called system.txt 1.2 3 4 567 8 9He 11 Hg Is H 15 Be 17 Mc Li 20 Write a one-line sed command that replaces the second number in every line with the string "system", without the quotes. For example, after running the appropriate sed command, the following would be output to the terminal 1 system 3 4 5 system 7 8 9 He system Hg Is H 15 Be 17 Mc Li system c) Consider the following file called swap.txt