Basic - Unix: Unix and the Shell Fall 2026

• Submission Instructions
• Preface
• Redirection
• Pipeline
• Files
• Conclusion

Submission Instructions

This homework will be submitted as a repository on the EECS GitLab server. The repository you submit will be a private Project with the name/path eecs201-basic-unix with akamil added as a Reporter. The branch main will be the one that is checked.

To finish the submission process and get your submission score, you will need to run the autograder. You will need to SSH into the course server (see Basic - Intro):

local$ ssh uniqname@peritia.eecs.umich.edu

(the local$ referring to a shell prompt on your system)

and then run eecs201-test:

peritia$ eecs201-test basic-unix

(the peritia$ referring to a shell prompt on the server)

The repository should have the following directory structure, starting from the repository’s root:

/
|-- report.txt
|-- 1-redirection
  |-- p1.sh
  |-- p2.sh
  |-- p3.sh
|-- 2-pipeline
  |-- p1.sh
  |-- p2.sh
|-- 3-files
  |-- p1.sh
  |-- p2.sh

Preface

This assignment should work fine on both Linux and macOS.

In this assignment you’ll be provided yet another zipped archive containing some starter empty files and scripts. Use your preferred tool to retrieve this file and extract it (see Basic - Git 1 if you need a review).

https://www.eecs.umich.edu/courses/eecs201/fa2026/files/assignments/basic-unix.tar.gz

Initialize a Git repository inside of the extracted basic-unix directory as per the submission instructions.

Redirection

Recall from class that we can redirect the inputs and outputs of a command. echo is a command that will print out a string (taking into account any expansions you embed in it). For example, I could use echo "Welcome $HOME" to print out Welcome /home/akamil. Try modifying this command so that it saves that output to a file.

cd into the 1-redirection directory. Inside you will see three shell script files: p1.sh, p2.sh, and p3.sh. Open the files in your preferred text editor and follow their instructions. Remember that shell scripts are literally shell commands you type at a the command line, just saved inside of a file. You can test and evaluate things at the terminal itself! To run files, as an example you can run $ ./p1.sh to run p1.sh.

Pipeline

Recall from class that commands can be chained together to form a pipeline, where one process passes its output to the input of the next. For example, this pipeline cat file1 file2 file3 | rev would concatenate three files and output the result with cat and then reverse the output of cat with rev.

cd into the 2-pipeline directory. Inside you will see two shell script files: p1.sh and p2.sh, as well as baby_names and grades, which serve as input data for the two scripts, respectively. Likewise, open the files in your preferred text editor and follow their instructions. Be sure to check out the baby_names and grades files to see their structure as you figure out your solutions.

Files

Recall from class that files have metadata that correspond to what permissions various users have for interacting with them: read, write, execute. These bits are grouped together to form a 3-bit octal (base 8) digit (which decimal, base 10, can represent regardless), in the order of rwx (read, write, execute). If you are unfamiliar with binary (base 2) representation, it’s like decimal except each place is a power of 2, and the only option for each place is 0 or 1. For example, 110 is

1 * 2^2 + 1 * 2^1 + 0 * 2^0 = 4 + 2 + 0 = 6

If we look at what that means for permission bits, 110 maps to rwx (read, write, execute), where 1 means permission and 0 means no permission, so that means that an octal 6 means “readable and writable”.

These files also have metadata that track ownership: what user owns the file and what group owns the file. Together, a file has three sets of these permission bits, one set of three corresponding to permissions for the user owner, one set for the group owner, and one set for everyone else not the user and not in the group (“other”). Thus, we can have an octal triplet such as 740, with 7 (rwx) for the user who owns it, 4 (r--) for the group that owns it, and 0 (---) for others.

cd into the 3-files directory. Inside you will see two shell script files: p1.sh and p2.sh. Likewise, open the files in your preferred text editor and follow their instructions. All you need to do for these two files is to provide the octal triplet on the right hand side of the assignment of the mode variable. If you want to test out your triplet, you can either create a file (e.g. via touch) and directly use chmod with the octal triplet on that file e.g. $ chmod 777 file-path-here, or create a file and then run the script with the created file as an argument e.g. $ ./p1.sh file-path-here.

Conclusion

1. Add and commit any changes you intend to submit.

2. Create a file called report.txt.

3. On the first line provide an integer time in minutes of how long it took for you to complete this assignment.

4. On the second line and beyond, write down what you learned while doing this assignment. If you already knew how to do all of this, put down “N/A”.

5. Add and commit this report.txt file.

6. Run the autograder!