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Your First Commands (The Ones You'll Use Forever)

Open a terminal. See that prompt? That's your new best friend. Or worst enemy. Depends on the day.

Let me show you the commands you'll use every single day. These aren't optional. These are essential.

The Terminal (How to Actually Open It)​

On Linux: Ctrl + Alt + T. That's it.

On Mac: Cmd + Space, type "Terminal". Or use iTerm2 (it's better).

On Windows: Use WSL. Or Git Bash. But really, use WSL.

Remote (SSH):

ssh username@server-ip

That's how you connect to servers. You'll do this a lot.

Understanding the Prompt​

When you open a terminal, you see something like:

ubuntu@server:~$

Let me break that down:

  • ubuntu - Your username
  • @server - The computer name
  • ~ - Where you are (~ means home directory)
  • $ - You're a regular user (# means root)

The ~ is important. It means "home". Like your house. Everything starts from home.

pwd: Where Am I?​

pwd

That's it. It tells you where you are.

When to use: Always. When you're lost, pwd tells you where you are.

Real example:

$ pwd
/home/ubuntu

You're in your home directory. Simple.

ls: What's Here?​

ls

Lists what's in the current directory. You'll use this constantly.

Basic usage:

ls                    # What's here?
ls -l                 # More details
ls -a                 # Show hidden files too
ls -la                # Both (this is what you'll use most)

The -la combo: Long format (-l) plus all files (-a). This is your most common command.

Real example:

$ ls -la
total 24
drwxr-xr-x 3 ubuntu ubuntu 4096 Dec 28 10:30 .
drwxr-xr-x 5 ubuntu ubuntu 4096 Dec 28 09:15 ..
-rw-r--r-- 1 ubuntu ubuntu  220 Dec 28 10:30 .bashrc
-rw-r--r-- 1 ubuntu ubuntu 1234 Dec 28 10:25 file.txt
drwxr-xr-x 2 ubuntu ubuntu 4096 Dec 28 10:20 projects

That's a lot of information. Don't worry about understanding it all now. Just know: ls -la shows you everything.

cd: Moving Around​

cd /path/to/dir       # Go somewhere
cd ~                  # Go home
cd                    # Also go home
cd ..                 # Go up one level
cd ../..              # Go up two levels

Navigation basics:

  • / = root (top level)
  • ~ = home (your directory)
  • . = current directory
  • .. = parent directory (one level up)

Real example:

$ pwd
/home/ubuntu
$ cd /etc
$ pwd
/etc
$ cd ~
$ pwd
/home/ubuntu

Pro tip: cd - goes back to where you were. Useful when you're jumping around.

cat: See File Contents​

cat filename

Shows file contents. Simple.

Real example:

$ cat /etc/hostname
server1

When to use: Quick file viewing. For long files, use less (we'll cover that).

mkdir: Create Directories​

mkdir dirname
mkdir -p path/to/dir  # Create parent directories too

Real example:

$ mkdir projects
$ mkdir -p projects/2024/january

The -p flag creates parent directories if they don't exist. Useful.

touch: Create Empty Files​

touch filename

Creates an empty file. Or updates the timestamp if it exists.

Real example:

$ touch test.txt
$ ls -la test.txt
-rw-r--r-- 1 ubuntu ubuntu 0 Dec 28 10:30 test.txt

Zero bytes. Empty file. That's it.

cp: Copy Files​

cp source destination
cp -r dir1 dir2       # Copy directory (recursive)

Real example:

$ cp file.txt file_backup.txt
$ cp -r projects projects_backup

The -r flag is for directories. Remember it.

mv: Move or Rename​

mv source destination

Moves files. Or renames them. Same command.

Real example:

$ mv oldname.txt newname.txt  # Rename
$ mv file.txt /tmp/           # Move

Pro tip: mv is also how you rename. There's no separate rename command.

rm: Delete (Be Careful)​

rm filename
rm -r dirname        # Delete directory
rm -rf dirname       # Force delete (dangerous)

Real example:

$ rm test.txt
$ rm -r old_directory

Warning: rm -rf is dangerous. It deletes without asking. Be careful.

Pro tip: There's no undo. Deleted is deleted. Be sure before you delete.

Getting Help​

man: The Manual​

man command

Shows the manual for a command. Everything is documented.

Real example:

$ man ls

Press q to quit. Use arrow keys to scroll.

--help: Quick Help​

command --help

Shorter help. Usually enough.

Real example:

$ ls --help

Your First Practice Session​

Let's actually do this:

# See where you are
pwd

# See what's here
ls -la

# Go home
cd ~

# Create a test directory
mkdir test_linux

# Go into it
cd test_linux

# Create a file
touch hello.txt

# See it
ls -la

# Go back home
cd ~

# Delete the test directory
rm -r test_linux

Do that. Actually type it. Don't just read it. That's how you learn.

Common Mistakes (I've Made These)​

  1. Spaces in paths: cd /home/user/my folder doesn't work. Use quotes: cd "/home/user/my folder" or escape: cd /home/user/my\ folder

  2. Case sensitivity: File.txt and file.txt are different. Linux cares about case.

  3. Forgetting sudo: Some commands need root. You'll forget sudo a lot. It's fine. Just add it.

  4. Deleting wrong thing: Always double-check before rm. There's no undo.

What's Next?​

Now that you know the basics, let's dive into Essential Commands. We'll cover the commands you'll use every day. The ones that actually matter.

Or practice these first. Your call. But get comfortable with these before moving on.

Personal note: When I started, I typed ls about a thousand times just to see what was there. That's fine. Get comfortable. These commands become muscle memory. Just practice.