Files

One of the basic principles in Unix and Linux states: Everything is a file!. Data files, directories, information about hardware devices in the system, information about processes, or important system configuration parameters are all represented as files.

The following types of files exist:

• inode - a data structure that describes a file system object.

• Files are always opened from user space with a name.

• The pair filename and inode is called a link.

• Regular files = bytes of data.

• Directories = mapping between file names and inodes (links).

• Hard links = multiple links connect different names to the same inode.

• Symbolic links = like regular files that contain the full path of the linked files.

• Special files = block device files, character device files, named pipes, Unix domain sockets.