Creating files

Folders were mkdir. Files have two flavors of creation, depending on whether you want them empty or already containing something.

The empty way: touch

The simplest:

touch hello.txt

Run ls. There’s a new file called hello.txt. It’s empty — zero bytes, nothing in it.

touch is named for what it does in old Unix folklore: it touches a file. If the file doesn’t exist, it’s created empty. If it already exists, its “last modified” time is bumped but the contents stay untouched.

You’ll use touch mostly when you need a placeholder file to exist — maybe a tool expects to find a file there, even an empty one.

You can make several at once:

touch readme.md notes.txt todo.txt

Three empty files, one keystroke.

The “with something in it” way: echo >

More useful: create a file that already has content. Try:

echo "Hello, terminal." > greeting.txt

Two new ideas are crammed into that line, and they show up everywhere from here on:

• echo prints whatever you give it. Try echo "hi" on its own — it just prints hi back at you.
• > is the redirect arrow. It says “don’t print the result to my screen — write it into this file instead.”

So that command is: “Print Hello, terminal., but instead of showing it on screen, save it to greeting.txt.”

Run ls and you’ll see greeting.txt. To peek inside, use cat:

cat greeting.txt

That prints the contents straight to your screen. (You’ll learn more file-reading tools in Level 2.)

The footgun nobody warns you about

The single > overwrites the file. If greeting.txt already had something in it, that something is gone. Forever. No undo. No “are you sure?” No trash bin to recover from.

Use >> (two arrows) to append instead — add to the end without erasing what’s there:

echo "And another line." >> greeting.txt

Now cat greeting.txt shows both lines. The rule:

• > overwrites
• >> adds to the end

This is one of the rules that bites everyone once. After the first time, you never forget.

What you’ve learned

• touch <file> — make an empty file (or update its modified time).
• echo "text" > <file> — create a file with text in it. Overwrites.
• echo "text" >> <file> — add text to the end of a file.

You can now create files and folders. The next three lessons cover the three things you’ll do with them every day: copy, move, delete.