The Essential Commands

You know what the shell is and how its loop works. Now let's fill your hands. There are thousands of commands out there, but the truth is you'll reach for the same small handful constantly - looking around, moving between folders, reading files, and making/copying/moving/deleting things. Learn these nine well and you can navigate any system with confidence.

Type along in your own terminal. Doing it once teaches more than reading it five times.

The transcripts below show a Mac/Linux shell (bash or zsh). PowerShell on Windows has built-in equivalents and even understands many of these names as aliases (ls, cd, cat work there too). Where it differs in a way that matters, it's noted.

The anatomy of a command

Almost every command you'll ever type follows the same three-part shape. See it once and every command afterward is readable:

   ls   -l   Documents
   │    │     │
   │    │     └── ARGUMENT  - what to act on (here: a folder)
   │    └──────── OPTION/FLAG - how to do it (here: "-l" = long, detailed listing)
   └───────────── COMMAND  - the program to run (here: "ls", "list")

• The command is the name of the program to run - always first.
• Options (also called flags) change how it runs. They usually start with a dash: a single dash for short forms (-l, -a), two dashes for long, readable forms (--all, --help). They're optional; the command has sensible defaults without them.
• Arguments are what the command acts on - a filename, a folder, some text.

Parts are separated by spaces. That one fact - spaces separate the pieces - is behind a gotcha we'll hit with filenames shortly, so keep it in mind.

📝 Terminology. "Option" and "flag" mean the same thing - a setting like -l that tweaks a command's behavior. People use both words interchangeably; don't let the two names fool you into thinking they're different.

💡 Key point. Almost any command accepts --help (or -h), which prints a summary of its options and arguments. When you forget how something works, ls --help is faster and safer than guessing.

pwd - where am I right now?

The shell is always "standing inside" exactly one folder, called your current working directory. Everything you do happens relative to it, so the first question is always where am I?

ada@laptop:~$ pwd
/home/ada

What just happened: pwd ("print working directory") reported the full path of the folder you're currently in: /home/ada. That /home/ada is the same place the prompt's ~ was standing in for - ~ is just shorthand for your home folder. Whenever you feel lost, pwd re-orients you. It only reports; it changes nothing.

ls - what's in here?

ada@laptop:~$ ls
Desktop  Documents  Downloads  notes.txt  photo.jpg

What just happened: ls ("list") showed the contents of your current folder - three folders and two files. By default it gives you the bare names. Ask for more detail with -l:

ada@laptop:~$ ls -l
total 20
drwxr-xr-x  2 ada  ada  4096 Jun 18 09:14 Desktop
drwxr-xr-x  5 ada  ada  4096 Jun 19 11:02 Documents
drwxr-xr-x  3 ada  ada  4096 Jun 17 16:30 Downloads
-rw-r--r--  1 ada  ada   132 Jun 19 10:45 notes.txt
-rw-r--r--  1 ada  ada  8841 Jun 15 13:20 photo.jpg

What just happened: The -l flag switched ls into a "long," detailed listing - one item per line with its permissions, owner, size in bytes, and last-modified date. The leading d (as on Desktop) marks a directory; a leading - marks a regular file. You don't need to decode every column today; the point is that the same command gives you the answer at the level of detail you ask for.

⚠️ Gotcha. By default ls hides files whose names start with a dot (like .git or .bashrc) - these "dotfiles" are config files meant to stay out of the way. If a file seems missing, try ls -a ("all") to reveal the hidden ones. They were always there; ls was just being tidy.

cd - move to another folder

ada@laptop:~$ cd Documents
ada@laptop:~/Documents$ pwd
/home/ada/Documents

What just happened: cd Documents ("change directory") moved you into the Documents folder. Notice the prompt updated - ~ became ~/Documents - and pwd confirms you're now at /home/ada/Documents. Your shell is now standing in a different room, so ls and everything else will act there.

A few cd moves worth memorizing, because you'll use them constantly:

ada@laptop:~/Documents$ cd ..
ada@laptop:~$ cd
ada@laptop:~$

What just happened: cd .. went up one level - .. always means "the parent folder," so you went from Documents back to /home/ada. Then plain cd with nothing after it jumped you straight back to your home folder from wherever you were. (cd - is a handy third: it returns you to the folder you were in just before - like a "back" button.)

📝 Terminology. A path is the address of a file or folder. Documents is a relative path (relative to where you are now); /home/ada/Documents is an absolute path (the full address from the top). . means "here," .. means "one level up," and ~ means "my home folder." If paths in general feel shaky, the sibling guide /guides/the-filesystem-explained is the deep dive.

cat - dump a file's contents to the screen

ada@laptop:~$ cat notes.txt
Buy milk
Call the dentist
Finish the terminal guide

What just happened: cat printed the entire contents of notes.txt straight into your terminal. It's the fastest way to glance at a short file without opening an editor. (The odd name is short for "concatenate" - its original job was joining files together - but day to day you'll use it to peek at one.)

⚠️ Gotcha. cat dumps the whole file at once. On a short file that's perfect; on a 10,000-line log it floods your screen and scrolls everything useful off the top. For anything long, use less instead.

less - read a long file calmly, one screen at a time

ada@laptop:~$ less server.log
2026-06-19 11:02:14  INFO  server started on port 3000
2026-06-19 11:02:15  INFO  connected to database
2026-06-19 11:03:01  WARN  slow query (1.2s)
...
:

What just happened: less opened the file in a scrollable viewer instead of dumping it. That : at the bottom is less waiting for you - it has taken over the screen. Use the arrow keys or Space to scroll, type /word then Enter to search for "word," and press q to quit back to your prompt.

⚠️ Gotcha. The first time less (or a similar pager) takes over your screen, it's easy to feel trapped - none of your normal commands seem to work, because less is intercepting your keys. The way out is always the same: press q. Plain git log, man, and other commands open pagers too; q quits all of them.

mkdir - make a new folder

ada@laptop:~$ mkdir projects
ada@laptop:~$ ls
Desktop  Documents  Downloads  notes.txt  photo.jpg  projects

What just happened: mkdir projects ("make directory") created a new, empty folder named projects, and the follow-up ls confirms it's there. Nothing is inside it yet - it's an empty room ready for you to cd into and start working.

cp - copy a file (the original stays put)

ada@laptop:~$ cp notes.txt notes-backup.txt
ada@laptop:~$ ls
Desktop  Documents  Downloads  notes-backup.txt  notes.txt  photo.jpg  projects

What just happened: cp ("copy") made a duplicate of notes.txt named notes-backup.txt. The shape is always cp <source> <destination> - from first, to second. The original notes.txt is untouched; you now have two files. (To copy a whole folder and everything inside it, you need cp -r - the -r flag means "recursive," i.e. include the contents.)

mv - move or rename (the original does not stay)

ada@laptop:~$ mv notes-backup.txt projects/
ada@laptop:~$ ls projects
notes-backup.txt

What just happened: mv ("move") relocated notes-backup.txt into the projects folder - it's now there and no longer in the home folder. Same <source> <destination> shape as cp, but mv doesn't leave a copy behind.

Here's the part that surprises people: renaming and moving are the same operation. "Move this file to a new name in the same folder" is a rename:

ada@laptop:~$ mv notes.txt todo.txt
ada@laptop:~$ ls
Desktop  Documents  Downloads  photo.jpg  projects  todo.txt

What just happened: Giving mv a destination that's just a different name in the same folder renamed notes.txt to todo.txt. There is no separate "rename" command in the shell - mv is it. That feels odd at first, then perfectly natural.

rm - delete a file (and this one needs your full attention)

ada@laptop:~$ rm todo.txt
ada@laptop:~$ ls
Desktop  Documents  Downloads  photo.jpg  projects

What just happened: rm ("remove") deleted todo.txt. Notice what didn't happen: no confirmation prompt, no "are you sure?", and the command printed nothing at all. Silence means it worked. todo.txt is gone, and the only sign is that it's no longer in the ls output.

⚠️ Gotcha - read this twice. rm does not move files to a Recycle Bin or Trash. There is no undo. When you rm something, the shell asks the OS to delete it immediately and permanently - it does not pass through any safety net the desktop gives you. This is the precision from Phase 1 cutting the other way: the terminal does exactly what you said, instantly. Treat rm with respect:

• Run ls first to confirm you're deleting what you think you are.
• Be extremely careful with rm -r (recursive - deletes a folder and everything inside it). It's powerful and unforgiving.
• If you want a confirmation prompt, rm -i asks before each delete. A good habit while you're new.

🪖 War story. Every seasoned developer has, at least once, deleted the wrong thing with rm and felt that specific cold drop in the stomach. It's a rite of passage precisely because there's no undo. The fix isn't fear - it's the habit above: look before you delete.

The gotcha that spans all of these: spaces in filenames

Remember from the anatomy section that spaces separate the pieces of a command. So what happens when a filename itself contains a space?

ada@laptop:~$ cat my notes.txt
cat: my: No such file or directory
cat: notes.txt: No such file or directory

What just happened: You meant one file called my notes.txt, but the shell saw the space and split it into two arguments - my and notes.txt - and went looking for two separate files that don't exist. The shell isn't being difficult; it genuinely can't tell your filename-space from a separator-space unless you tell it.

The fix is to quote the name, which tells the shell "treat all of this as one piece":

ada@laptop:~$ cat "my notes.txt"
Remember to quote filenames with spaces.

What just happened: The quotes wrapped my notes.txt into a single argument, so cat got the one file you meant and printed it. Single quotes work too. This is why filenames with spaces are a small headache in the terminal - and why many developers name files my-notes.txt or my_notes.txt to sidestep it entirely.

Recap

1. Anatomy: command [options] [arguments], separated by spaces. Options (flags) tweak how; arguments say what. --help reminds you of both.
2. pwd - where am I? ls (-l detailed, -a shows hidden) - what's here?
3. cd <folder> - move in; cd .. up; cd home; cd - back.
4. cat - dump a short file; less - scroll a long one (press q to quit).
5. mkdir - make a folder. cp <from> <to> - copy (original stays). mv <from> <to> - move or rename (original doesn't stay).
6. rm - delete, permanently, no undo, no Recycle Bin. Look before you leap; rm -r deletes whole folders.
7. Quote filenames with spaces ("my notes.txt"), because spaces normally separate command pieces.

You can now navigate and manage files by hand. Next, the features that make the terminal genuinely powerful - chaining commands together and letting the shell do the tedious parts for you.

← Phase 1: What the Terminal and Shell Actually Are · Guide overview · Phase 3: The Real Power →

Try it yourself

Here's a real (but fake) shell - nothing leaves your browser. Try ls, cd projects, cat readme.txt, mkdir demo, then tree: