NEED 5,7,10

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 lf respectively. And what will be printed for expression 123.345 with this format string? 8) (3 points) Rewrite the following loop so that its body is empty: for (i = 0; i