Chapter 4

Time to get our hands dirty — Linux isn’t just about looking at files, it’s about making, breaking, moving, and linking them like a boss.

In this chapter, you’ll learn:

• How to create directories (mkdir)

• How to copy stuff (cp)

• How to move and rename stuff (mv)

• How to delete (danger zone!) with rm

• How to link files together with ln

• How to use wildcards to work with many files at once

And yes… we’re going to build a playground so you don’t blow up your system while practicing. 😏

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🎮 Step 1: Build a Playground

Let’s not experiment on important files — that’s like learning to drive by practicing in a Ferrari showroom.

Make a safe place in your home directory:

cd ~
mkdir playground
cd playground

From now on, all examples happen in ~/playground.

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🏗️ mkdir — Make New Directories

Think of mkdir as “summon a new folder.”

mkdir new_folder

Cool tricks:

• mkdir -p project/src/assets → makes a whole tree at once 🌳

• mkdir -v demo → Linux politely tells you what it made

👉 Try:

mkdir test1 test2 test3
ls

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📋 cp — Copy Files Like a Wizard

cp = duplicate files. It doesn’t teleport them, it clones them.

cp source.txt copy.txt

Useful options:

• -i → ask before overwriting (cp -i a b)

• -r → copy folders recursively (cp -r dir1 dir2)

• -u → only copy if newer

👉 Playground Test:

echo "Hello" > hello.txt
cp hello.txt hello_copy.txt
ls

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🚚 mv — Move or Rename

This one is sneaky: it both renames and moves.

mv old.txt new.txt   # rename
mv file.txt dir/     # move into a folder

Options:

• -i → ask before overwriting

👉 Try this:

mkdir stuff
mv hello_copy.txt stuff/
ls stuff

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💀 rm — Remove (Danger Zone!)

The most feared command. rm permanently deletes things. There’s no recycle bin. No undo. Just void.

rm file.txt
rm -r folder/

Options:

• -i → confirm before deleting

• -r → delete folders recursively

• -f → force delete, no questions asked 😈

⚠️ Scary Story Time: You wanted to delete .html files:

rm *.html     # ✅ correct
rm * .html    # ❌ deletes EVERYTHING, then complains about ".html"

👉 Safety Tip: Always test wildcards with ls first:

ls *.html

If it shows the right files, then press ↑ and replace ls with rm.

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🔗 ln — Hard & Symbolic Links

Links are like extra doorways to the same file.

🔹 Hard Links

• Multiple names for one file

• File survives until all links are gone

• Can’t cross file systems, can’t link directories

Example:

ln hello.txt hello_hard

Now hello.txt and hello_hard are the same file. Edit one, the other changes too.

🔹 Symbolic Links (Symlinks)

• Modern, flexible

• Works like Windows shortcuts

• Can link across file systems, can point to directories

• If the original dies, the symlink is “broken” (ls often shows it in red)

Example:

ln -s hello.txt hello_symlink

👉 Test it:

echo "Linked!" >> hello_symlink
cat hello.txt

You wrote to the symlink, the original changed. Magic! ✨

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🎭 Wildcards — Work With Many Files at Once

Wildcards = pattern matching for filenames.

Wildcard	Meaning	Example
*	Matches any characters	ls *.txt → all .txt files
?	Matches a single character	ls file?.txt → file1.txt but not file10.txt
[abc]	Matches a, b, or c	ls [abc]*
[!0-9]	Matches anything not a digit	ls [!0-9]*
[[:upper:]]	Uppercase letters	ls [[:upper:]]*

👉 Try:

touch file1.txt file2.txt fileA.txt test.TXT
ls f*
ls file?.txt
ls [[:upper:]]*

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✅ Recap

• mkdir makes folders

• cp copies

• mv moves/renames

• rm deletes (handle with care!)

• ln makes links (hard vs symlink)

• Wildcards let you target groups of files like a pro

And remember: always practice inside your playground before unleashing these commands on your real system.

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