basilysf1709 / operating-systems

Creating a shell, Scheduling Algorithms and Memory Simulation

Operating Systems Creating a shell

Name: Basil Yusuf

Course: Operating Systems (CIS*3110)

Date: 6th February, 2021

Version: 1.0

Objective

In this assignment you are to implement a simple UNIX shell program. A shell is simply a program that conveniently allows you to run other programs. Read up on the bash shell to see what it does.

Specification

Your shell must support the functions described below. The functions are grouped into 3 sets. You may develop the functions in any order, but they are grouped in order of difficulty. It would be prudent to get the simpler functions working first. With each function there are some suggestions for POSIX system calls that may help with the construction of the function. These suggestions are not exhaustive, nor do you necessarily need to use them. They are there to stimulate your thinking.

Assumptions and Limitations

• We are assuming that the default path is /bin/
• There's an assumption that & will always be at the end
• history command does not work with > or <

User Guide

• After being in the correct directory with the "makefile" and "myShell.c".
• Type the command "make"
• And then, type "./myShell"
• You have to press enter once to set the Profile file

Test Plan:

The application provided here is robust. To test its functionality, the following test cases can be used.

1. SET 1 - Ensuring that Set 1 Functionality works properly. Test: Performing a trial run

Test

• For exit() type exit in the shell.

Result:

• The exit command will kill all the processes and exit.

Test

• For no arguments like ls type ls and press enter.

Result:

• The command uses execv and should display the list of elements.

Test

• For commands with arguments type ls -l and press enter.

Result:

• The command uses execv and should display the list of elements with the L Flag.

Test

• For Background Processes type sleep 5 & and press enter.

Result:

• The command uses waitpid and executes the process in the background.

2. SET 2 - Ensuring that Set 2 Functionality works properly. Test: Performing a trial run

Test

• For Output redirection type ls -lt > foo.txt and press enter.

Result:

• The command uses freopen to write the output to a file.

Test

• For Input redirection type sort < foo.txt and press enter.

Result:

• The command uses freopen to read from a file.

Test

• For Piping type ls -lt | wc and press enter.

Result:

• The command uses pipe(), dup2() to make the pipe functionality work.

3. SET 3 - Ensuring that Set 3 Functionality works properly. Test: Performing a trial run

Test

• For Environment Variables type echo $myPATH and press enter.

Result:

• The command uses execv functionality, and it reads from the profile file to save and output the environment variables.

Test

• For Environment Variables type echo $myPATH and press enter.

Result:

• The command uses execv functionality, and it reads from the profile file to save and output the environment variables.

Test

• For Profile File, go to the user's home directory to find all the environment variables in the file called CIS3110_profile.

Result:

• In the profile file, you'll find the environment variables.

Test

• For export, type export myPATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:$myHOME/bin and press enter.

Result:

• In the profile file, you can find that the path variable has been changed, and to test it, you can type echo $myPATH and enter.

Test

• For history, type history, history -c, orhistory n and press enter to get all the commands you have typed, to delete your history of commands, or to get the "n" number of history commands.

Result:

• In the profile file, you can find the history file named CIS3110_history.

Test

• For cd, type cd .. and press enter to change the current working directory.

Result:

• Shell's working directory will change.

Citations

-Took reference from CodeVault Youtube Channel for piping. -Took reference from Stack Overflow. -Took reference from documentation provided by Professor Deborah Stacey

Future Enhancements

The code is modular in nature. It has the ability, however, to be built up from even smaller components in a truly modular way utilizing more powerful tools provided by the C language. As a result, in future generations of this code, little restructuring would make it more portable.

Most of the components have been broken down to simple functions. These functions can be changed, and updated to make future enhancements. It should be pretty easy to change the code without changing the overall behavior.

Operating Systems Scheduling Algorithms

Name: Basil Yusuf Course: cis3110 Assignment: Scheduling Algorithms Date: 19th March, 2022

compiling

Compile using: make Copy paste this command: ./simcpu [-d] [-v] [-r quantum] < input_file

Things to take care of

1. Make sure the file is of the correct format

Operating Systems Memory Simulation

Name: Basil Yusuf Course: Operating Systems (CIS*3110) Date: April 10th, 2022 Version: 1.0

Compiling Instructions: make

Running Instructions:

1. First fit: ./hole [File Name] first
2. Worst fit: ./hole [File Name] worst
3. Best fit: ./hole [File Name] best
4. Next fit: ./hole [File Name] next