(2) Write a Unix program that does the following

You run the program in command line using the following syntax:

you_program_name file_name

Where file_name is the name of a text file under the current directory

When the program starts, it does the following

If filename is not specified in the command line, or if there are too many parameters, display the correct usage and then exit. Otherwise,

It forks three (3) child processes

The parent process then displays its own PID information only once, then waits for all its child processes die (hint: use wait() for this.. The wait() system call suspends the calling process until one of its child processes dies.)

Let one child-process run the "ls -l" command (using the "execl" system call); Let another child-process run the "ps -ef" command; Let the third child-process display the content of the file (specified by file_name). You can use the program "more" or "cat" to display it. After all child processes terminate, the main process displays "main process terminates" then exits. This should be the last piece of information displayed by your program.