please write in C programming languageProgrammers, and other computer system professionals, frequently interact with computers using programs with the usual kinds of Graphic User Interfaces (GUIs). But often they also make frequent use of the much older command line style of interface, as when interacting with an operating system ( OS) shell. An OS shell is a program that presents the user with a plain-text (character oriented) interaction window in which the user types commands and program input and plain-text output may be displayed. The shell prints a prompt and then reads a line of characters typed by the user, which it interprets as a command followed by arguments. The command, which may be built into the shell or a program installed in the system, is executed, sometimes prompting the user for more input and/or printing output. When the command is finished, the shell program loops back to the point where it prints a command prompt for the user. Although it is not part of the operating system, it makes heavy use of many operating system features and thus serves as a good example of how the system calls can be used. Building a Simple Shell You will develop a simple UNIX shell (command interpreter). Your shell will implement the following commands