4) (2 points) parent directory into a text file Clist.txt 5) (2 points) Write a single line UNIX command to run an executable C program testC at background and mail the output to email address test@ gsu.edu. 6) (2 points) Write a single line UNIX command to output the returned value of last command 7) (2 points) In the format string %6.21f, explain the meaning of 6, 2 and 1f respectively. And what will be printed for expression 123.345 with this format string