Glossary

Filesystem hierarchy

The standard layout of directories under /.

Linux has one tree rooted at /, with a standardized layout: /etc holds configuration, /var holds data that grows (logs, databases, web roots), /usr holds installed programs, /home holds user directories, /tmp is scratch space, /opt hosts self-contained third-party apps.

Disks and network shares do not get drive letters — they are mounted onto directories inside this tree. Knowing the layout turns an unfamiliar server from a maze into a map: configs here, logs there.

See it in practice

$ ls / && du -sh /var/log

The top-level map, then the size of the directory that most often fills a server’s disk.

Where you'll meet it