• Coordinating processes with signals and shared memory
• You should first create a sub-directory under your home directory. The name should be os2 and put the exercise in that directory.
• deadline: 04/21, 00:01am
• example code for signal handling
• example code for shared memory

Description of exercise:
First, study the code in Figure 5.5 on textbook. The parent thread creates the child thread to complete the summation and the parent writes the result out. In this exercise, you are asked to simulate such behaviour with processes.

• You should use fork() to create the child process.
• Parent should pass the parameter to the child AFTER the fork(). Of course, such data passing is done by shared memory. However, parent must also notify the child that such parameter passing is completed. So parent must send child a signal and child must catch such signal.
• After child has got the parameter and completed the calculations, it also transfers the sum to parent. The scenario is similar. Child will send parent a signal and parent must catch it.
• Finally, parent print the sum out.
• A process can send a signal to another one by kill(). Try to read the man page of kill. (Try "man -s 2 kill")