Overview

This assignment will give you an introduction to UNIX processes; you will learn how to find out information on and manage running tasks. Additionally, you will learn how to schedule processes to run automatically for you with cron and at. As of the creation of this assignment, however, at and cron are disabled on the instructional accounts for security concerns, so you won't actually be able to use thm. We are in the process of talking to instructional support to find a solution.

Reading

Das: Ch. 8

Part 1 - Questions

Answer the following questions and bring them in for a tutor to evaluate:

1. What keystroke sequence do you execute to suspend a running terminal process that is in the foreground?
2. When terminating a process, why is it important to try 'kill' before doing 'kill -9'?

Part 2 - Managing What's Running

Use 'script' (Section 2.8) to record your session, so you can show it to a tutor.

1. Execute the program 'cat' with no arguments. This will cause the program to wait for user input and appear to be a hung process. Pretend this actually IS a hung process and execute the neccessary commands to do the following tasks from within the same session:
   1. Suspend the process
   2. Discover the process ID
   3. Kill the process
2. Again, execute the program 'cat' with no arguments and pretend it is a hung process. Login to your account in a seperate session and execute the neccessary commands to do the following:
   1. Discover the process ID
   2. Kill the process
3. Execute a command which will find all files in /usr/sww/opt and its subdirectories that contain the character sequence 'java' in their filename, and have this output stored to the file 'javafiles' in your home directory. This will take a while to finish, so make sure to have the process run in the background, so you can do other tasks while you wait. How can you verify that the process is still running and not a hung?

Part 3 - Crontab

Due to security restrictions, most of the instructional machines restrict usage of cron and at. Your cs9e accounts, however, are allowed to use these on one instructional machine. For this part of the assignment, you will need to use torus.cs.berkeley.edu

Create a cron job which updates a web-accessible document every 15 minutes, http://inst.eecs.berkeley.edu/~<your login>/disk_usage.txt. This document should contain the time of last update and a summary of your disk quota usage Example:

Mon Sep 11 14:13:34 PDT 2006
Disk quotas for cs9e-1 (uid 20620):
Filesystem     usage  quota  limit    timeleft  files  quota  limit    timeleft
/home/ff       17408 2147483644 2147483644               1089     -1     -1            

(Hint: You can see your quota usage with the 'quota' command.)

You will need to show the tutor the crontab entry as well as the web output.

Part 1

• Student correctly and intelligently answers all questsions

Part 2

• Student correctly answers all questions and provides a transcript showing their interaction with the system

Part 3

• Student can adequately explain how cron works and how their page is being updated.
• Student's web output is correct and updated hourly