<<<<<< 4 BOTTOM LINES CLEANING SUBROUTINE >>>>>>

BOTCLEAN

If they want to quit, do so

ENCORE5

     <<<<<< TIME POSE SUBROUTINE >>>>>>>>>

PAUSE

If they want to quit, do so

    <<<<<< SOME CLEANING SUBROUTINE >>>>>>

SOMECLEAN

 AH:

ENCORE1

    <<<<<< REVIEW CLEANING SUBROUTINE >>>>>>

CLEAN

If they want to quit, do so

ENCORE

    <<<<<< CLEAN THE INSIDE OF BOUNDED ARE ONLY >>>>>

BOX

                       SOLUTION                       

GO

  Let us solve this example together!

  Step 1 is to establish a clear goal.

  The primary goal is to: spawn 5 processes, wait for their       

                          completion and report their exit status.

  The secondary goal is to: Learn how to use process control functions.

 Let's assume first that the standard I/O file stdio.h will be required ...

   #include <stdio.h>

 The five processes will be called: proc1, proc2,

 proc3, proc4, and proc5.  If you want to define and initialize 

 a character array called process[], what would the first part of 

 the declaration be?  (Don't give the array size, it will be 

 determined by the initialization values.)

 Answer here:     

 That is correct!

 You've got it on the 2nd try.

 Good!  Now you understand the concept!

 Start with char followed by  * 

 Try char *process[]

FORGET1

 The correct answer is char *process[]

   #include <stdio.h>

   char *process[] = {"proc1", "proc2", "proc3", "proc4", "proc5"};

 The process counter i, the process status status,

 the process id procid and the exit status exitstat

 should all be of what type?

 Answer here:      

 That is correct!

 You've got it on the 2nd try.

 Good!, Now you understand the concept!

 It is a type that takes whole numbers.

 Try an int or a short

FORGET2

 The correct answer is int or short

   #include <stdio.h>

   char *process[] = {"proc1", "proc2", "proc3", "proc4", "proc5"};

   main()

   {

       int i, status;

       int procid, exitstat=0;

           :

           :

   }

  Which program segment will fork all 5 processes, and then execute

  the child processes? (Remember, fork() returns 0 to the child

  process and the process number of the child to the parent.)

          a   for (i=0; i < 5; i++) {

                 if ((procid = fork()) == 0)

                     if (execv(process[i], NULL)== -1)

                         exit(1); break; }

          b   for (i=0; i < 5; i++) {

                 if ((procid = fork()) <> 0)

                     if (execv(process[i], NULL)== -1)

                         exit(1); break; } }

          c   for (i=0; i < 5; i++) {

                 if ((procid = fork()) == 0)

                     if (execv(process[i], NULL)<> -1)

                         exit(1); break; } }

 Select one:      

 That is correct!

 You've got it on the 2nd try.

 Good!  Now you understand the concept!

 Think about what fork() returns!

 Think about what execv() returns!

FORGET3

 The correct choice is a.  Choices b and c need to 

 have <> replaced by ==!  Therefore:

   #include <stdio.h>

   char *process[] = {"proc1", "proc2", "proc3", "proc4", "proc5"};

   main()

   {

       int i, status;

       int procid, exitstat=0;

       for (i=0; i < 5; i++) {

         if ((procid = fork()) == 0) {  /* child process */

            if (execv(process[i], NULL)== -1)

               exit(1);

               break;  /* if fork fails*/

         }

       }

  The parent process will wait for the child processes and report 

  the outcome. The algorithm for achieving this is:

   if ((procid != 0) {  /* then the parent process */

       for (i = 1; i<= 5; i++) {

          procid = wait(&status);

          if (status != 0) {

             exitstat++;

             printf("PROCESS %d FAILED\n", procid);

          }

          else

             printf("Process %d SUCCESSFUL\n", procid);

        }

    }

    exit(exitstat);  /* exit Control Process */