A file name is hidden from a normal directory listing if it begins with a . When the li command is entered with the -a flag, the hidden files are listed along with regular files and directories. The path name of a file consists of the name of every directory that precedes it in the file tree structure. Only the final component of a path name can contain the name of a regular file. All other components in a path name must be directories.
Path names can be absolute or relative.
The files in the following chapter are system files. These files are created and maintained by the operating system and are necessary for the system to perform its many functions. System files are used by many commands and subroutines to perform operations. These files can only be changed by a user with root authority.