Required

ex00. z

Create a file containing the letter “Z”

echo "Z" > z

ex01. testShell00

Create a file called testShell00, then make it 40 bytes long. The easiest way to do that to fill it with 40 ASCII characters like digits or letters.

424242424242424242424242424242424242424

Now we also need to match the permissions using the chmod command, which works as follows:

chmod 445 testShell00

Refer to https://www.theserverside.com/blog/Coffee-Talk-Java-News-Stories-and-Opinions/how-permissions-chmod-with-numbers-command-explained-777-rwx-unix to know how to set the number, each digit is essentially calculated.

To match the timestamp, we can use:

touch -d "1 Jun 2026 23:42" testShell00

Then create a tar using

tar -cf testShell00.tar testShell00

and remove the original testShell00, leave only testShell00.tar

ex02. Oh yeah, mooore…

Similar process to ex01 with the permissions and timestamps, the only exception is that test0 and test2 are directories, test5 is a hard link to test3, and test6 is a symbolic link pointing to test0.

Think of a symbolic link as a shortcut, what is put into test6 goes into test0 and vise versa. A hard link is similar, but differs in how it is stored.

DON'T FORGET TO MAKE THE FILES THE RIGHT SIZE! If you want a 1 byte file you need to do:

printf "a" > file.name

Replace file.name with your file's name.

To give symlinks a new timestamp you need to add the -h attribute to the touch command

To create the symlink:

ln -s test0 test6

and to create the hardlink:

ln test5 test3

Please make sure to do it in this order to avoid messing it up:

1. Create files, folders, links
2. Change timestamps
3. Change permissions

For reference, I also made this shell script that you can use:

#!/bin/bash

# This script creates the notoriously tedious exo2.tar file for Shell00
# because running these commands by hand is hell

# STEP 0: Create sandbox so we don't suck in unintended files
mkdir exo2
cd exo2

# STEP 1: Create all files, dirs and links
mkdir test0
mkdir test2

printf "XXXX" > test1
printf "X" > test3
printf "XX" > test4

ln -s test0 test6
ln test3 test5

# STEP 2: Set timestamps
touch -d "1 Jun 2026 20:47" test0
touch -d "1 Jun 2026 21:46" test1
touch -d "1 Jun 2026 22:45" test2
touch -d "1 Jun 2026 23:44" test3
touch -d "1 Jun 2026 23:43" test4
touch -d "1 Jun 2026 23:44" test5
touch -h -d "1 Jun 2026 22:20" test6

# STEP 3: Set all permissions
chmod 404 test3
chmod 404 test5
chmod 714 test1
chmod 715 test0
chmod 504 test2
chmod 641 test4

# STEP 4: tar it all up
tar -cf ../exo2.tar *

# STEP 5: Exit sandbox
cd ..

Remember that you should only upload exo2.tar and nothing else in ex02 otherwise Moulinette might complain (I can't tell you for sure)

ex03: id_ed25519_pub

Using ssh-keygen, you can generate SSH keys. These always come with a private and public keypair.

ssh-keygen -t ed25519

Leave the default values for all 3 prompts by just leaving them empty and now your public key file is in ~/.ssh/id_ed25519.pub, copy it to your ex03 folder, rename and you’re done.

ex04: midLS

The command is:

ls -tmp

and that’s because:

• -t sorts by time; newest first
• -m adds commas to the list
• -p adds the / to directory names

These flags can be found in the man page for ls, which can be opened by running

man ls

ex05: GiT commit

This goes into git_commit.sh

#!/bin/bash
git log -5 --format="%H"

• #!/bin/bash is the shebang, it tells the shell what this script is designed to run with, in this case bash
• git log shows the commit log
• -5 limits it to 5 entries
• —format=”%H” makes git only show the full commit hash (%H is a placeholder that tells git to show the full hash)

These flags can be found in git man pages. You can also open man pages for sub-commands like git log sometimes, for example

man git logs

Finally to make the script executable, chmod +x git_commit.sh

Optional

ex06: gitignore

This goes into git_ignore.sh

#!/bin/bash
git ls-files --others --ignored --exclude-standard

• git ls-files lists the files that are in the repository.
• --others displays files that are not in the git index.
• --ignored displays the ignored files that were defined in .gitignore.
• --exclude-standard lists the files deleted by default.

ex07: diff

First of all you need to download the resources.tar.gz file from the 42 Infra page. To unpack it in the terminal, tar command can be used as follows:

tar -xf resources.tar.gz

Make sure to be in the directory where the file was downloaded

Now to create b, we need to use patch to apply sw.diff to a, which will then turn a into our needed file b.

patch a sw.diff

To confirm the output is correct, you should get:

mobeid@c1r3s1 ~/Downloads> cat -e a
Episode V, A NEW H0PE It is a period of civil war$
Rebel spaceships, striking from a hidden base, have won their first victory against the evil Galactic Empire. $
During the battle, Rebel spies managed to steal secret plans to the Empire's ultimate weapon, the STAR DEATH, an armored space station with enough power to destroy an entire planet.$
$
$
Pursued by the Empire's sinister agents,$
Princess Mehdi races home aboard her starship, custodian of the stolen plans that can save her people and restore the dictatorship to the galaxie..$
$
$
$
$

-e tells cat to show a $ at every new line

Rename a to b by using mv (used for moving files but that also renames it)

mv a b

Delete the sw.diff and resources.tar.gz.

ex08: clean

Inside the clean file:

find . -type f \( -name "*~" -o -name "#*#" \) -print -delete

• The brackets tell find to take multiple of these arguments. They are prepended by \ to tell the shell to not interpret the brackets as script syntax
• -type f tells it to look for files
• -name tells it to look for a name using wildcards
• -print prints out the found results
• -delete deletes them after finding them

These can be found in man pages as well. Just read man pages.

ex09: ft_magic

A plain text magic file has lines that tell the file command how to identify a certain file type. For our 42 file type, we need to check if after the 42nd byte, it contains the string “42”

The structure of the line is basically

[offset] TAB string [string] [type]

• [offset] is the number of bytes starting counting from 0. In our case it’s 41 cuz 0 is the first number, not 1
• Where TAB is shown you need to press Tab in your text editor. Use a command line text editor like nano or nvim as not all graphical editors actually put tab characters, some put regular spaces.
• string tells file that it needs to look for a string
• [string] is the string in question, 42 in our case
• [type] is the name of the filetype, in this case 42 file

So the final magic file is:

41	string 42 42 file

To verify if it works, create a file containing 42 spaces and then follow it up by "42", then run:

file -m ft_magic my42file

It should report it as a 42 file. Any other file type should not.

Browse source files 10 files in Shell00. They open in Notepad.

This page is Shell00's notes, rendered here from the README on GitHub. Last read on 20 October 2026 at 18:42 UTC.