Lesson 6 of 29 beginner 6 min read

The filesystem hierarchy

Key takeaways Linux keeps everything in one tree that starts at the root, / — there are no C: or D: drive letters. Learn the few neighbourhoods you’ll actually visit, then learn to name any spot two ways: an absolute path from / (/home/you/notes.txt) or a relative path from where you’re standing (notes.txt). ~ is always shorthand for your home directory. Get these and the terminal stops feeling like a maze. New to the shell? Start with your first commands.

When you came from Windows or a Mac’s Finder, files felt scattered across drives and folders with no obvious order. Linux is tidier than it first looks: there is exactly one tree, every location has a name, and the layout follows a shared convention. Once you can picture the tree, cd and ls become a walk through a neighbourhood you know.

One tree, no drive letters

On Windows each disk gets its own letter — C:, D:, a USB stick as E:. Linux does it differently. There is a single tree, and its top is the root directory, written as a plain forward slash: /. Everything — programs, your documents, system settings, even hardware — hangs off / somewhere.

So where do extra disks go? They are mounted into the tree at an empty folder, rather than becoming a separate drive. A USB stick might appear at /media/you/USB, an extra hard disk at /mnt/data. To you it’s just another folder deeper in the same tree; there’s no separate E: to switch to. One tree, many places — that’s the whole model.

The folders that matter

The tree has many branches, but a beginner only meets a handful. Here are the neighbourhoods worth knowing by name:

/home — where your files live. Each user gets a folder here, e.g. /home/matt. This is where you’ll spend almost all your time.
/etc — system-wide configuration. Plain-text settings files for the machine and its services live here (the name is often read as “et cetera”).
/var — variable data that changes as the system runs: logs, mail queues, caches. When something misbehaves, /var/log is where you look — see monitoring & logs.
/usr and /bin — the programs. Most installed software and the commands you type (like ls and cd) live under these.
/tmp — scratch space for temporary files. Anything here may be wiped on reboot, so never keep something you care about in /tmp.
/root — the administrator’s home directory. Note this is not the same as /; it just happens to share the word “root”.
/dev — devices. Disks, terminals, and other hardware appear here as special files (more on that below).
/opt and /mnt — /opt holds some optional add-on software; /mnt is a common spot to mount extra disks.

You don’t need to memorise every branch. Recognising these on sight is enough to navigate confidently. This layout is a shared convention — the Filesystem Hierarchy Standard (FHS) — which is why most Linux systems put things in the same places.

Absolute vs. relative paths

A path is just the name of a location in the tree. There are two ways to write one, and knowing which is which saves a lot of confusion.

An absolute path starts at the root, /, and spells out the full route:

/home/you/notes.txt

Because it begins at /, it means the same file no matter where you currently are. Absolute paths are unambiguous.

A relative path starts from your current directory — wherever you happen to be standing. If you’re already in /home/you, then:

notes.txt        the file in this directory
./notes.txt      the same thing — . means "here"
../up            go up one level first, then into "up"

Two special names show up constantly:

. means this directory (the one you’re in).
.. means the parent directory, one level up toward the root.

And one very handy shorthand:

~ (tilde) means your home directory, usually /home/yourname. So ~/notes.txt is the same file as /home/yourname/notes.txt, from anywhere.

A quick rule of thumb: if a path starts with / it’s absolute; if it starts with ~ it’s home-relative; anything else is relative to where you are right now.

Everything is a file

Linux takes a striking shortcut: almost everything is presented as a file. Not just your documents — hardware and system information show up as files too. A disk appears under /dev (for example /dev/sda); live details about the running system appear under /proc. You won’t touch these on day one, but it’s worth knowing the idea exists, so that reading from a “file” to talk to a device later doesn’t come as a surprise. It’s part of what makes the command line so composable: the same tools that read text files can often read a device too.

Try it

Open a terminal and walk the tree. pwd (print working directory) tells you where you are; cd (change directory) moves you:

$ pwd
/home/you
$ cd /etc            # jump somewhere by absolute path
$ pwd
/etc
$ cd ..              # go up one level (to /)
$ pwd
/
$ cd home/you        # relative path from here (no leading slash)
$ pwd
/home/you
$ cd ~               # ~ takes you straight home
$ pwd
/home/you

Notice the pattern: a leading / means “start from the root,” while a name without one means “start from here.” .. steps up, ~ warps home.

Quick check: where do system-wide configuration files conventionally live?

Recap

Linux has one tree starting at the root / — no drive letters; disks mount into the tree.
Key neighbourhoods: /home (your files), /etc (config), /var (logs and changing data), /usr and /bin (programs), /tmp (scratch).
An absolute path starts at / and means the same thing everywhere; a relative path starts from your current directory.
~ is your home; . is here; .. is one level up.
Almost everything is a file, including devices (/dev) and system info (/proc).

Next up: navigating & listing files

Frequently asked questions

What is the root directory in Linux?

The root directory is /, the single top of the filesystem tree. Every file and folder on the system lives somewhere below it, and external disks are mounted into the tree rather than given separate drive letters. Note that / (the root of the tree) is different from /root, which is the home directory of the administrator account.

What is the difference between an absolute and a relative path?

An absolute path starts at the root directory / and names a location in full, like /home/you/notes.txt, so it means the same thing from anywhere. A relative path starts from your current directory, like notes.txt or ../up, so what it points to depends on where you are.

What does the ~ symbol mean in Linux?

~ (tilde) is shorthand for your home directory, usually /home/yourname. So ~/notes.txt and /home/yourname/notes.txt point to the same file, and typing cd with no argument takes you home as well.

Where do configuration files live on Linux?

System-wide configuration conventionally lives in /etc. Logs and other data that changes as the system runs live in /var. Your own settings live in your home directory, often in hidden files or folders whose names start with a dot.