Installation guide

system, you specify a location (the mount point under the system root
directory) to which the file system will attach.
The root directory of a mounted file system is also its mount point. Only
one system root directory can exist because the system uses the root
directory as its source for system initialization files. Consequently, file
systems are mounted under the system root directory.
7.1.5 Directories and File Types
The operating system views files as bit streams, allowing you to define and
handle on-disk data, named pipes, UNIX domain sockets, and terminals as
files. This object-type transparency provides a simple mechanism for
defining and working with a wide variety of storage and communication
facilities. The operating system handles the various levels of abstraction as
it organizes and manages its internal activities.
While you notice only the external interface, you should understand the
various file types recognized by the system. The system supports the
following file types:
• Regular files contain data in the form of a program, a text file, or source
code, for example.
• Directories are a type of regular file and contain the names of files or
other directories.
• Character and block device files identify physical and pseudodevices on
the system.
• UNIX domain socket files provide a connection between network
processes. The
socket system call creates socket files.
• Named pipes are device files that communicating processes operating
on a host machine use.
• Linked files point to target files or directories. A linked file contains the
name of the target file. A symbolically linked file and its target file can
be located on the same file system or on different file systems. A file
with a hard link and its target file must be located on the same file
system.
7.1.6 Device Special Files
Device special files represent physical devices, pseudodevices, and named
pipes. The /dev directory contains device special files. Device special files
serve as the link between the system and the device drivers. Each device
special file corresponds to a physical device (for example, a disk, tape,
printer, or terminal) or a pseudodevice (for example, a network interface, a
7–12 Administering the UNIX File System