转自：http://serverfault.com/questions/24523/meaning-of-directories-on-unix-and-unix-like-systems
/bin - Binaries.
/boot - Files required for booting.
/dev - Device files.
/etc - Etcctera. The name is inherited from the earliest Unixes, which is when it became the spot to put config-files.
/home - Where Home directories are kept.
/lib - Where code libraries are kept.
/media - A more modern directory, but where removable media gets mounted.
/mnt - Where temporary file-systems are mounted.
/opt - Where opt
tional add-on software is installed. This is discrete from /usr/local/ for reasons I'll get to later.
/run - Where run
time variable data is kept.
/sbin - Where super-binaries are stores. These usually only work with root.
/usr - Another directory inherited from the Unixes of old, it stands for "user". This directory should be sharable between hosts, and can be NFS mounted to multiple hosts safely. It can be mounted read-only safely. Also as per Debian Wiki, /usr is UNIX System Resources.
/var - Another directory inherited from the Unixes of old, it stands for "variable". This is where system data that varies may be stored. Such things as spool and cache directories may be located here. If a program needs to write to the local file-system and isn't serving that data to someone directly, it'll go here.
/srv - Stands for "serve". This directory is intended for static files that are served out. /srv/http
would be for static websites, /srv/ftp for an FTP server.
