A shell is a program dedicated to allowing an operator to launch other programs. It can be as simple as a menu or as complex as a COM-interfaceable GUI with gr

A shell is a program dedicated to allowing an operator to launch other programs. It can be as simple as a menu or as complex as a COM-interfaceable GUI with graphical desktop metaphor. It's often configured to but not strictly required to automatically launch on user login. Any user-space executable can issue system calls, the shell isn't special there.