What Happens when you execute a command? Ans. When you enter 'ls' command to look at the contents of your current working directory, UNIX does a series of things to create an environment for 'ls' and the run it: The shell has UNIX perform a fork. This creates a new process that the shell will use to run the ls program. The shell has UNIX perform an exec of the 'ls' program. This replaces the shell program and data with the program and data for 'ls' and then starts running that new program. The 'ls' program is loaded into the new process context, replacing the text and data of the shell. The 'ls' program performs its task, listing the contents of the current directory.