After reading section 5, you should understand the basics of processes in UNIX (e.g., how fork() works, how memory is shared, how processes communicate). After reading section 6, you should undersatnd the basics of the shell. For instance, you should be able to describe what happens if you type sh into the UNIX shell (how many processes would be running?). Sections 7-10 wrap up the authors' discussions on UNIX.

If you want to test your understanding of UNIX further, check out Question 7 from the 2015 quiz (solutions).

As you read, think about the following:

• What 6.033 concepts are exemplified by UNIX?
• What design principles, or objectives, do you think the authors were following as they developed UNIX?

Question for Recitation

Before you come to this recitation, write up (on paper) a brief answer to the following (really—we don't need more than a couple sentences for each question). If your TA has requested that you email your answer to them, you may do that instead, but it should still be handed in before your recitation begins.

Your answers to these questions should be in your own words, not direct quotations from the paper.

• What does the UNIX shell do?
• How does it work?
• Why is it useful?