In Linux and Unix everything is a file. Directories are files, files are files, and devices are files. Devices are usually referred to as nodes; however, they are still files.
Linux and Unix file systems are organized in a hierarchical, tree-like structure. The highest level of the file system is the / or root directory. All other files and directories exist under the root directory. For example, /home/jebediah/cheeses.odt shows the correct full path to the cheeses.odt file that exists in the jebediah directory, which is under the home directory, which in turn is under the root (/) directory.
Underneath the root (/) directory is a set of important directories common to most Linux distributions. The following is a listing of common directories that are directly under the root (/) directory:
/bin - aplicações binárias importantes
/boot - boot configuration files, kernels, and other files needed at boot time
/dev - os ficheiros de dispositivos (do inglês device)
/etc - ficheiros de configuração, scripts de arranque, etc.
/home -
home directories for different
users
/initrd - used when creating a customized initrd boot process
/lib - bibliotecas de sistema (do inglês libraries)
/lost+found - fornece um sistema de perdidos e achados para ficheiros que existem sob o directório root (/).
/media - automatically mounted (loaded) partitions on your hard drive and removable media such as CDs, digital cameras, etc.
/mnt - manually mounted filesystems on your hard drive
/opt - provides a location for optional (3rd party) applications to be installed
/proc - directório especial dinâmico que mantém informação acerca do estado do sistema, incluindo os processos actuais em execução.
/root - root user's home directory, pronounced "slash-root"
/sbin - binários de sistema importantes
/srv - can contain files that are served to other systems
/sys - ficheiros de sistema (do inglês system)
/tmp - ficheiros temporários
/usr - aplicações e ficheiros que estão maioritariamente disponíveis para acesso de todos os utilizadores.
/var - ficheiros variáveis tais como registos e bases de dados