Write the Code in C language.

1. Create a program that does the following.

- Creates a master process with two child processes using fork()

- The master process writes two files child1.txt containing the line child 1 and child2.txt containing the line child 2

- Each of the two child processes waits one second then reads the contents of their text file and prints the contents.

- Reading and writing files between process is a simplified method of IPC

2.Create a program that does the following.

- Creates a parent and child process using fork().

- The child process sleeps for 1 second and prints Child process.

- The parent process instead of immediately executing, waits for the child process to terminate using the wait() function before printing Parent process.

- The parent process must check the return status of the child process after it has finished waiting.

- See the following for more information on forking and waiting:

http://www.cs.rutgers.edu/~pxk/416/notes/c-tutorials/

3. Create a program that does the following.

- Create a global array length five, moving_sum, and initialize it to zeros.

- Prompts a user for fives numbers

- For each number creates a thread

- Each thread executes a function factorial which takes a struct containing the number and index of the number entered (0 - 4) and does the following:

- Calculates the factorial (e.g. 5! = 5x4x3x2x1 = 120, 0! = 1).

- Using a semaphore, gets the previous value in the moving_sum[index-1] if the value at that index is > 0. If the value is retrieved it is added to the factorial calculated and the sum is added to moving_sum[index].

- Until the value in moving_sum[index-1] is > 0, performs an infinite loop, each time it must perform signal and wait to allow other threads access to the critical section. - After all threads finish (using join()) print the contents of moving_sum