Using sed For help using sed, you may find the tutorial http://www.grymoire.com/Unix/Sed.html useful. a) Consider the following file called phone.txt: containing some DFW area phone numbers, except that the area code (i.e., the first three digits) are backwards and do not include the parentheses around the area code as follows 279 680-0035 412 328-2197 964 432-8492 718 780-4972 Write a one-line sed command that reverses the order of the three digits in the area code and adds the needed parentheses around the area code so that after running the appropriate sed command, the following would be output to the terminal (972) 680-0035 (214) 328-2197 (469) 432-8492 (817) 780-4972 b) The // character sequence is often known as C++ style or single-line comments while the /* .. / character sequence is often known as C-style or multi-line comments. As an example, assume the following myprog.c file that has a mix of both C-style and C++ style comments IN This is a test of how this works #include int main I/ declare some variables here int num1 = 4 float num2 = 3.5 print the result printf("The result is %fin", num! * num2); // this does it does it work? return 0; Write a one-line sed command that transforms all of the C++ style i.e., single-line comments) to the C-style (ie., multi-line comments) so that after running the appropriate sed command, the following would be output to the terminal: /* This is a test of how this works #include int main * declare some variables here */ int num1 = 4 float num2 = 3.5 print the result */ printf("The result is %fn", num 1 * num2); ,-this does it does it work? return 0