The File System
The Linux environment file structure is a hierarchy of directories, subdirectories, and files that are grouped together for a specific purpose.

Root Directory -The topmost directory in the file system hierarchy. The root directory is required for the operating system to function and contains critical system files.

Subdirectory - Any directory below another directory.

Parent Directory - The directory immediately above a subdirectory. Each subdirectory has only one parent, but a parent directory can have many subdirectories.

  • The /home directory contains the user's directory.
  • The /etc directory contains system administration files, such as the passwd and hosts files.
  • The /opt directory contains unbundled and third-party software applications.
  • The /usr directory contains executable commands, system administration utilities and library routines. Much of the third party software is stored in the /usr/local sub-directory.