Everything in Linux can
be reduced to a file. Partitions are associated with files such as /dev/hda1.
Hardware components are associated with files such as /dev/modem. Detected
devices are documented as files in the /proc directory. The File system Hierarchy
Standard (FHS) is the official way to organize files in Unix and Linux
directories.
Linux/Unix File systems
and Directories
Several major directories
are associated with all modern Unix/Linux operating systems. These directories
organize user files, drivers, kernels, logs, programs, utilities, and more into
different categories. The standardization of the FHS makes it easier for users
of other Unix-based operating systems to understand the basics of Linux. Every
FHS starts with the root directory, also known by its label, the single forward
slash (/). All of the other directories shown in Table are subdirectories of
the root directory. Unless they are mounted separately, you can also find their
files on the same partition as the root directory.
/
|
The
root directory, the top-level directory in the FHS. All other directories are
subdirectories of root, which is always mounted on some partition. All
directories that are not mounted on a separate partition are included in the
root directory?s partition.
|
/bin
|
Essential
command line utilities. Should not be mounted separately; otherwise, it could
be difficult to get to these utilities when using a rescue disk.
|
/boot
|
Includes
Linux startup files, including the Linux kernel.
Can be small; 16MB is usually adequate for a typical modular kernel. If you
use multiple kernels, such as for testing a kernel upgrade, increase the size
of this partition accordingly.
|
/etc
|
Most
basic configuration files.
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/dev
|
Hardware
and software device drivers for everything from floppy drives to terminals.
Do not mount this directory on a separate partition.
|
/home
|
Home
directories for almost every user.
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/lib
|
Program
libraries for the kernel and various command line utilities. Do not mount
this directory on a separate partition.
|
/mnt
|
The
mount point for removable media, including floppy drives, CD-ROMs, and Zip
disks.
|
/opt
|
Applications
such as WordPerfect or StarOffice.
|
/proc
|
Currently
running kernel-related processes, including device assignments such as IRQ ports,
I/O addresses, and DMA channels.
|
/root
|
The
home directory of the root user.
|
/sbin
|
System
administration commands. Don't mount this directory separately.
|
/tmp
|
Temporary
files. By default, Red Hat Linux deletes all files in this directory
periodically.
|
/usr
|
Small
programs accessible to all users. Includes many system administration commands
and utilities.
|
/var
|
Variable
data, including log files and printer spools.
|
Types
of Files Used by Linux
When working with Linux,
you need to be aware of the fact that there are a number of different file
types used by the file system. This is another area where the Linux file system
differs significantly from the Windows file system. With a Windows file system
you basically have two entry types in the file system:
- Directory
- File
Granted, you can have
normal files, hidden files, shortcut files, word processing files, executable
files, and so on. However, these are all simple variations of the basic file
when working with Windows.
With Linux, however, there are a variety of different file types used by the
file system. These include the file types shown in Table
File Type
|
Description
|
Regular files
|
These
files are similar to those used by the file systems of other operating
systems—for example, executable files, OpenOffice.org files, images, text
configuration files, etc.
|
Links
|
These
files are pointers that point to other files in the file system.
|
FIFOs
|
FIFO
stands for First In First Out. These are special files used to move data from
one running process on the system to another. A FIFO file is basically a
queue where the first chunk of data added to the queue is the first chunk of
data removed from the queue. Data can only move in one direction through a
FIFO.
|
Sockets
|
Sockets
are similar to FIFOs in that they are used to transfer information
between sockets. With a socket, however, data can move bi-directionally.
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Some of the Configuration Files in /etc Directory that
you should remember
File
|
Function
|
/etc/fstab
|
Lists
the partitions and file systems that will be automatically mounted when the
system boots.
|
/etc/group
|
Contains
local group definitions.
|
/etc/grub.conf
|
Contains
configuration parameters for the GRUB bootloader (assuming it’s being used on
the system).
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/etc/hosts
|
Contains
a list of hostname-to-IP address mappings the system can use
to resolve hostnames.
|
/etc/inittab
|
Contains
configuration parameters for the init process.
|
/etc/init.d/
|
A
subdirectory that contains startup scripts for services installed on the
system. On a Fedora or Red Hat system, these are located in /etc/rc.d/init.d.
|
/etc/modules.conf
|
Contains
configuration parameters for your kernel modules.
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/etc/passwd
|
Contains
your system user accounts.
|
/etc/shadow
|
Contains
encrypted passwords for your user accounts.
|
/etc/X11/
|
Contains
configuration files for X Windows.
|
|
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