Lecture 7 review • What are environment variables? – A set of dynamic values that can affect the execution of a process – A process by default inherit the set of environment variables from the parent process • Most commands are executed from the shell program they inherit environment variables from the shell process. • How can we see the environment variables in the shell process? • How can we modify the value of environment variables in shell? • Give two methods to access environment variables in a program. Lecture 7 review • What is a signal? • How does a process typically react to a signal? • How many different ways a process can react to a signal? • How to install a signal handle? • How to block a signal?