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