File Creation Basics - Learn mkdir/touch/echo/cat

File Creation Basics - Linux Command Fundamentals
Reading time: ~12 min Level: Beginner

What You'll Learn

  • Create new directories (folders) with mkdir
  • Create empty files with touch
  • Output text and write to files with echo
  • Display file contents with cat

Target Audience: Those who've learned pwd/cd/ls, ready for the next step in file operations

Table of Contents

  1. Introduction: Lina's Next Step
  2. mkdir - Create Directories
  3. touch - Create Empty Files
  4. echo - Output Text
  5. cat - View File Contents
  6. Mini Challenges - Practice Now
  7. Common Pitfalls and Solutions
  8. Today's 3-Line Summary
  9. What to Learn Next

Introduction: Lina's Next Step

Lina: Linny-senpai! I've got pwd, cd, and ls down now!
Linny-senpai: Awesome! Let's move to the next step then. This time, we'll learn how to "create files."
Lina: Create files... On Windows, I'd right-click and select "New." Can I do that with commands too?
Linny-senpai: Absolutely! Today we'll learn four commands: mkdir (create directories), touch (create files), echo (output text), and cat (display files). Once you master these, you'll be able to create files and write content to them.

mkdir - Create Directories

Linny-senpai: First up is the mkdir command. It stands for "Make Directory" and creates new directories (folders).
Lina: A directory is like a box that holds files, right?
Linny-senpai: Exactly! Let's create a practice directory first.

Basic Usage

$ mkdir practice
Lina: Huh? Nothing showed up. Is that okay?
Linny-senpai: In Linux, commands typically "say nothing when successful." Use ls to verify. 
$ ls
documents  downloads  practice  pictures

Key Point: Make it a habit to verify mkdir results with ls. In Linux, "silence means success" - if there's no error, nothing is displayed.

Create Multiple Levels at Once (-p option)

Lina: I want to create lesson1 inside practice...
Linny-senpai: Great question! The -p option creates parent directories along the way. 
$ mkdir -p practice/lesson1/exercises
Lina: So practice, lesson1, and exercises are all created at once!

touch - Create Empty Files

Linny-senpai: Next is the touch command. It creates empty files.
Lina: "Touch" means to touch something, right? Touching a file...?
Linny-senpai: Originally, its purpose is to "update a file's timestamp (last modified date)." But since it creates a new file if one doesn't exist, it's commonly used for file creation.

Basic Usage

$ touch memo.txt
$ ls
documents  downloads  memo.txt  practice  pictures
Lina: memo.txt was created! But it's empty inside, right?
Linny-senpai: Right. To write content, we'll use the next command: echo.

Create Multiple Files at Once

$ touch file1.txt file2.txt file3.txt
$ ls
file1.txt  file2.txt  file3.txt  memo.txt  ...

Key Point: touch can create multiple files at once by separating filenames with spaces.

echo - Output Text

Linny-senpai: The echo command outputs text strings. As the name suggests (like an echo), it returns whatever you input.

Display Text on Screen

$ echo Hello
Hello
$ echo "Hello, Linux World!"
Hello, Linux World!
Lina: The text I type just appears on screen. But this alone doesn't seem very useful...
Linny-senpai: I thought you might think that. But echo's real power is "writing to files."

Write to Files (Redirection)

$ echo "This is a memo" > memo.txt
Lina: What's the > symbol?
Linny-senpai: That's called "redirection" - it redirects text that would normally appear on screen into a file instead. Think of it like pointing a water faucet in a different direction. > means "overwrite," and >> means "append." 
$ echo "First line memo" > memo.txt
$ echo "Adding second line" >> memo.txt

Warning: Using > (overwrite) completely replaces the file contents. If you want to keep existing content, always use >> (append).

cat - View File Contents

Linny-senpai: Last is the cat command. Short for "concatenate" (pronounced con-CAT-en-ate, meaning "to join together"), it displays file contents.
Lina: I want to see what I wrote with echo!

Basic Usage

$ cat memo.txt
First line memo
Adding second line
Lina: Both lines are showing!
Linny-senpai: cat displays the entire file at once, making it handy for checking short files.

Concatenate and Display Multiple Files

$ echo "Contents of file 1" > file1.txt
$ echo "Contents of file 2" > file2.txt
$ cat file1.txt file2.txt
Contents of file 1
Contents of file 2

Key Point: When you specify multiple files with cat, it concatenates and displays them. That's where the name "concatenate" comes from.

Display with Line Numbers (-n option)

$ cat -n memo.txt
     1  First line memo
     2  Adding second line

Mini Challenges - Practice Now

Linny-senpai: Let's try some challenges using these four commands.

Challenge 1: Create a Practice Directory and Navigate Into It

Task: Create a directory called "my-project", navigate into it, and confirm your current location.

Show Hint

Use mkdir, cd, and pwd in sequence.

Show Solution 
$ mkdir my-project
$ cd my-project
$ pwd
/home/user/my-project

Note: The /home/user part will differ based on your username. As long as your username appears, you're good!

Challenge 2: Create a README File and Write Content

Task: Create an empty file called "README.txt", write a project name and creation date to it, then display the contents.

Show Hint

Use touch to create the file, echo > to overwrite, echo >> to append, and cat to display.

Show Solution 
$ touch README.txt
$ echo "Project Name: My First Project" > README.txt
$ echo "Created: 2026-02-02" >> README.txt
$ cat README.txt
Project Name: My First Project
Created: 2026-02-02

Challenge 3: Create Subdirectories and Organize Files

Task: Create a two-level directory "docs/notes" in one command, create "memo1.txt" and "memo2.txt" inside it, then list the files.

Show Hint

Use mkdir -p to create multiple levels at once, and touch can create multiple files at once.

Show Solution 
$ mkdir -p docs/notes
$ touch docs/notes/memo1.txt docs/notes/memo2.txt
$ ls docs/notes
memo1.txt  memo2.txt
Lina: Done! I'm starting to understand the flow: create a directory, create a file, write content, then verify!
Linny-senpai: Perfect! This workflow is something you'll use constantly in real work, so make it second nature.

Common Pitfalls and Solutions

Pitfall 1: Typos in Directory Names

Lina: I typed mkdir documets by mistake... I wanted "documents."
Linny-senpai: That's a common mistake. You can recreate it or rename it later with the mv command. Make it a habit to verify with ls.

Pitfall 2: Confusing Redirection Operators

Lina: I wanted to append with echo "more" > memo.txt but I accidentally overwrote everything...
Linny-senpai: That's a really common mistake. >> (two) for append, > (one) for overwrite. When in doubt, remember "two for adding."

Pitfall 3: Trying to Create a File in a Non-existent Directory

$ touch newdir/file.txt
touch: cannot touch 'newdir/file.txt': No such file or directory
Linny-senpai: touch doesn't automatically create directories. First run mkdir newdir, then touch.

Pitfall 4: Confusing Files and Directories

Lina: I tried to view a directory's contents with cat and got an error.
Linny-senpai: cat shows file contents. For directory contents, use ls. With ls -la, entries starting with "d" are directories, and those starting with "-" are files. Check and confirm.

Pitfall 5: Using Non-ASCII Characters in Filenames

Lina: Can I use characters like Japanese with mkdir?
Linny-senpai: Technically yes, but it's best to avoid it. It can cause encoding issues or make scripts harder to work with. Stick to alphanumeric characters, hyphens, and underscores for filenames.

Today's 3-Line Summary

  • mkdir creates directories; -p creates multiple levels at once
  • touch creates empty files; echo "content" > file writes to files
  • cat displays file contents; use >> for appending

What to Learn Next

Lina: I understand how to create files now! What should I learn next?
Linny-senpai: Next up is "copying," "moving," and "deleting" files. Once you learn cp, mv, and rm, you'll have mastered the basics of file operations. Check out File Operations Basics for details!

Master File Operations Through Practice

Once you've learned these four commands, solidify your knowledge by practicing hands-on challenges on Penguin Gym Linux.

Practice on Penguin Gym Linux Next Article: File Operations Basics