Using C++, you are to design a simple shell which implements a subset of the functionality of the Bourne Again Shell (Bash). The requirements for your shell are as follows: Continually prompt for textual user input on a command line. Parse user input according the the provided grammar (see below) When a user enters a well formed command, execute it in the same way as a shell. You must use the commands fork and exec to accomplish this. You may NOT use the C++ system() command. Allow users to pipe the standard output from one command to the input of another an arbitrary number of times. Support input redirection from a le and output redirection to a le. Allow users to specify whether the process will run in the background or foreground using an '&'. (Commands to run in the foreground do not have an '&', and commands that run in the background do)