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AIX Version 4 Files Reference
Chapter 5. Directories
Directories contain directory entries. Each
entry contains a file or subdirectory name and an i-node (index node reference)
number. To increase speed and enhance the use of disk space, the data in a file
is stored at various locations throughout the computer's memory. The i-node
contains the addresses used to locate all of the scattered blocks of data
associated with a file. The i-node also records other information about the
file, including time of modification and access, access modes, number of links,
file owner, and file type. It is possible to link several names for a file to
the same i-node by creating directory entries with the ln command.
Because directories often contain information
that should not be available to all users of the system, directory access can
be protected. See "File
Ownership and User Groups" in AIX Version 4.3 System User's Guide: Operating System and Devices for more information.
Understanding Types of Directories
Directories can be defined by the system
or the system administrator, or you can define your own directories. The
system-defined directories contain specific kinds of system files, such as
commands. At the top of the file system hierarchy is the system-defined root
directory. The root directory is represented by a / (slash) and usually
contains the following standard system-related directories:
/bin |
Symbolic link to the /usr/bin directory. In prior UNIX file
systems, the /bin directory contained user commands that now reside in
/usr/bin in the new file structure. |
/dev |
Contains device nodes for special files for local devices. The
/dev directory contains special files for tape drives, printers, disk
partitions, and terminals. |
/etc |
Contains configuration files that vary for each machine. Examples
include:
The /etc directory contains the files
generally used in system administration. Most of the commands that used to
reside in the /etc directory now reside in the /usr/sbin
directory. However, for compatibility, it contains symbolic links to the new
locations of some executable files. Examples include:
- /etc/chown is a symbolic link to the
/usr/bin/chown.
- /etc/exportvg is a symbolic link to the
/usr/sbin/exportvg.
|
/export |
Contains the directories and files on a server that are for remote
clients. |
/home |
Serves as a mount point for a file system containing user home
directories. The /home file system contains per-user files and
directories.
In a standalone machine, a separate local file
system is mounted over the /home directory. In a network, a server
might contain user files that should be accessible from several machines. In
this case, the server's copy of the /home directory is remotely mounted
onto a local /home file system. |
/lib |
Symbolic link to the /usr/lib directory, which contains
architecture-independent libraries with names in the form lib*.a. |
/sbin |
Contains files needed to boot the machine and mount the /usr
file system. Most of the commands used during booting come from the boot
image's RAM disk file system; therefore, very few commands reside in the
/sbin directory. |
/tmp |
Serves as a mount point for a file system that contains
system-generated temporary files. |
/u |
Symbolic link to the /home directory. |
/usr |
Serves as a mount point for a file system containing files that do
not change and can be shared by machines (such as executables and ASCII
documentation).
Standalone machines mount a separate local
file system over the /usr directory. Diskless and disk-poor machines
mount a directory from a remote server over the /usr file system. |
/var |
Serves as a mount point for files that vary on each machine. The
/var file system is configured as a file system since the files it
contains tend to grow. For example, it is a symbolic link to the
/usr/tmp directory, which contains temporary work files. |
Some directories, such as your login or home
directory ($HOME), are defined and customized by the system
administrator. When you log in to the operating system, the login directory is
the current directory. If you change directories using the cd command
without specifying a directory name, the login directory becomes the current
directory.
Related Information
Files,
Directories, and File Systems for Programmers in AIX General Programming Concepts: Writing and Debugging Programs introduces
i-nodes, file space allocation, and file, directory, and file system
subroutines.
File Systems and
Directories Overview in AIX Version 4.3 System User's Guide: Operating System and Devices introduces files and directories
and the commands that control them.
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