1. CS-3013 & CS-502 Operating Systems Summer 2006
Programming Project #1
CS-3013 & CS-502 Operating Systems Summer 2006
CS 3013 & CS 502 – Summer 2006
Programming Project #1

2. Programming Assignment
Write a command called doit to execute another command and print out statistics
Extend doit to become a basic shell that prompts for and executes commands
Extend your shell to shell2 to execute commands in the background
CS 3013 & CS 502 – Summer 2006
Programming Project #1

3. Purpose To practice using the fork and exec facilities of Unix/Linux
To learn how to find and use on-line documentation about system calls and system facilities.
man pages
To be accustomed to speaking directly with the operating system
CS 3013 & CS 502 – Summer 2006
Programming Project #1

4. Part 1: doit doit command:– Must execute on a CCC or CS Linux system
Take another command line as argument
Execute that command
Print out statistics about command
Must execute on a CCC or CS Linux system
May not use system() system call
Helpful hints:–
fork(), execve(), wait()
getrusage(), gettimeofday()
CS 3013 & CS 502 – Summer 2006
Programming Project #1

5. Part 1 (output) % doit cat /etc/motd
< print the current message of the day >
< statistics about the cat command >
CS 3013 & CS 502 – Summer 2006
Programming Project #1

6. Part 2: shell Repeatedly prompt for command lines
Execute each command and print out statistics, as in doit
Implement special “built-in” commands
exit
cd dir
Special conditions
Exit on end of file
Complain about illegal commands
Check for line length, number of arguments
CS 3013 & CS 502 – Summer 2006
Programming Project #1

7. Part 2 output % shell ==>cat /etc/motd
< print the current message of the day >
< statistics about the cat command >
==>cd dir
< current directory is changed to dir >
==>ls
< listing of files in current directory >
< statistics about this ls command >
==>exit
% < back to the Unix prompt >
CS 3013 & CS 502 – Summer 2006
Programming Project #1

8. Part 3: Background execution (shell2)
Modify shell to support execute commands in background, indicated by ‘&’ character
Causes shell to prompt for next command before previous command is complete
jobs built-in command lists background tasks in progress
Report completion at next opportunity
CS 3013 & CS 502 – Summer 2006
Programming Project #1

9. Part 3 output % shell2 ==>numbercrunch &
[1] < indicate background task #1, process id >
==>jobs
[1] numbercrunch
< print process id and command name for tasks >
==>ls
< listing of files in the current directory >
< statistics about this ls command >
==>cat /etc/motd
[1] Completed < indicate background job done >
< statistics about numbercrunch command >
< print the current message of the day >
< statistics about this cat command >
==>exit
% < back to Unix prompt >
CS 3013 & CS 502 – Summer 2006
Programming Project #1

10. Project submission Due Monday, June 1 at start of class
Submit via turnin
command = ‘/cs/bin/turnin’ on CCC machines
classname = ‘cs502’
assignment = ‘project1’
Bring copy of code, test case, and printout to class.
Put your name on all files!
CS 3013 & CS 502 – Summer 2006
Programming Project #1

11. Term Project Assignment
CS 3013 & CS 502 – Summer 2006
Programming Project #1