1.2 Filesystem and Paths

The Linux filesystem is a tree that grows from /. Disks, configuration, user directories, logs, programs, and mounted storage all live somewhere under this tree.

Common directories

You do not need to memorize everything at once. Start with this: user files live around /home, configuration around /etc, logs around /var/log.

Absolute and relative paths

A path starting with / is absolute:

/var/log/nginx/access.log

It starts from the root directory and does not depend on your current location.

A path that does not start with / is relative:

logs/app.log
../notes/today.md

It is resolved from the current working directory.

Four special path forms

• ~: the current user's home directory, such as /home/leaf.
• .: the current directory.
• ..: the parent directory.
• -: the previous directory, commonly used with cd -.

If you can explain these four symbols, many path problems become much easier.

What is a mount point?

In Linux, disks, USB drives, network storage, and container volumes can be attached to a directory. That directory is called a mount point. For example, a data disk might be mounted at /data, and then /data/uploads refers to files on that disk.

These commands help inspect disks and mounts:

df -h
mount
lsblk

df -h is common for disk space; lsblk is common for block-device structure.

A good path habit

Before entering or changing an unfamiliar directory, run:

pwd
ls

Before deleting, moving, or changing permissions, confirm that the path is truly the path you intend. Many production incidents happen because the command syntax was correct, but the location was wrong.