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NOTE: CentOS Enterprise Linux is built from the Red Hat Enterprise Linux source code. Other than logo and name changes CentOS Enterprise Linux is compatible with the equivalent Red Hat version. This document applies equally to both Red Hat and CentOS Enterprise Linux.
Chapter 4. The sysconfig Directory
The /etc/sysconfig/ directory contains
a variety of system configuration files for Red Hat Enterprise
Linux.
This chapter outlines some of the files found in the /etc/sysconfig/ directory, their function, and
their contents. The information in this chapter is not intended to
be complete, as many of these files have a variety of options that
are only used in very specific or rare circumstances.
The following files are normally found in the /etc/sysconfig/ directory:
 |
Note |
| |
If some of the files listed here are not present in the
/etc/sysconfig/ directory, the
corresponding program may not be installed.
|
The following sections offer descriptions of these files. Files
not listed here as well as extra file options found in the
/usr/share/doc/initscripts-<version-number>/sysconfig.txt file
(replace <version-number> with
the version of the initscripts package).
Alternatively, looking through the initscripts in the /etc/rc.d/ directory can prove helpful.
The /etc/sysconfig/amd file contains
various parameters used by amd; these
parameters allow for the automatic mounting and unmounting of file
systems.
The /etc/sysconfig/apmd file is used
by apmd to configure what power settings
to start/stop/change on suspend or resume. This file configures how
apmd functions at boot time, depending on
whether the hardware supports Advanced Power
Management (APM) or whether the user
has configured the system to use it. The apm daemon is a monitoring program that works with
power management code within the Linux kernel. It is capable of
alerting users to low battery power on laptops and other
power-related settings.
The /etc/sysconfig/arpwatch file is
used to pass arguments to the arpwatch
daemon at boot time. The arpwatch daemon
maintains a table of Ethernet MAC addresses and their IP address
pairings. By default, this file sets the owner of the arpwatch process to the user pcap as well as sends any messages to the
root mail queue. For more information
regarding available parameters for this file, refer to the
arpwatch man page.
The /etc/sysconfig/authconfig file
sets the authorization to be used on the host. It contains one or
more of the following lines:
-
USEMD5=<value>, where <value> is one
of the following:
-
USEKERBEROS=<value>, where <value> is one
of the following:
-
USELDAPAUTH=<value>, where <value> is one
of the following:
The /etc/sysconfig/autofs file defines
custom options for the automatic mounting of devices. This file
controls the operation of the automount daemons, which
automatically mount file systems when you use them and unmount them
after a period of inactivity. File systems can include network file
systems, CD-ROMs, diskettes, and other media.
The /etc/sysconfig/autofs file may
contain the following:
-
LOCALOPTIONS="<value>", where "<value>" is a string for defining machine
specific automount rules. The default value is an empty string
("").
-
DAEMONOPTIONS="<value>", where "<value>" is the timeout length in seconds
before unmounting the device. The default value is 60 seconds
("--timeout=60").
-
UNDERSCORETODOT=<value>, where <value> is a binary value that controls
whether to convert underscores in file names into dots. For
example, auto_home to auto.home and auto_mnt to
auto.mnt. The default value is 1
(true).
-
DISABLE_DIRECT=<value>, where <value> is a binary value that controls
whether to disable direct mount support, as the Linux
implementation does not conform to the Sun Microsystems'
automounter behavior. The default value is 1 (true), and allows for
compatibility with the Sun automounter options specification
syntax.
The /etc/sysconfig/clock file controls
the interpretation of values read from the system hardware
clock.
The correct values are:
-
UTC=<value>, where <value> is one
of the following boolean values:
-
ARC=<value>, where <value> is the
following:
-
true or yes
— The ARC console's 42-year time offset is in effect. This
setting is only for ARC- or AlphaBIOS-based Alpha systems.
-
false or no
— This value indicates that the normal UNIX epoch is in
use.
-
SRM=<value>, where <value> is the
following:
-
ZONE=<filename> — The time
zone file under /usr/share/zoneinfo that
/etc/localtime is a copy of. The file
contains information such as:
Earlier releases of Red Hat Enterprise Linux used the following
values (which are deprecated):
The /etc/sysconfig/desktop file
specifies the desktop for new users and the display manager to run
when entering runlevel 5.
Correct values are:
-
DESKTOP="<value>", where "<value>" is
one of the following:
-
DISPLAYMANAGER="<value>", where "<value>" is
one of the following:
-
GNOME — Selects the GNOME Display
Manager.
-
KDE — Selects the KDE Display
Manager.
-
XDM — Selects the X Display
Manager.
For more information, refer to Chapter 7
The X Window System.
The /etc/sysconfig/devlabel is the
devlabel configuration file. It should not
be modified by hand, but rather, configured using the /sbin/devlabel command.
For instructions on using the devlabel
command, refer to the chapter titled User-Defined Device Names in the Red Hat Enterprise Linux System Administration
Guide.
The /etc/sysconfig/dhcpd file is used
to pass arguments to the dhcpd daemon at
boot time. The dhcpd daemon implements the
Dynamic Host Configuration Protocol (DHCP) and the Internet
Bootstrap Protocol (BOOTP). DHCP and BOOTP assign hostnames to
machines on the network. For more information about what parameters
are available in this file, refer to the dhcpd man page.
The /etc/sysconfig/exim file allows
messages to be sent to one or more clients, routing the messages
over whatever networks are necessary. The file sets the default
values for exim to run. Its default values are set to run as a
background daemon and to check its queue each hour in case
something has backed up.
The values include:
-
DAEMON=<value>, where <value> is one
of the following:
-
QUEUE=1h which is given to exim as
-q$QUEUE. The -q
option is not given to exim if /etc/sysconfig/exim exists and QUEUE is empty or undefined.
The first time the system boots, the /sbin/init program calls the etc/rc.d/init.d/firstboot script, which in turn
launches the Setup Agent. This
application allows the user to install the latest updates as well
as additional applications and documentation.
The /etc/sysconfig/firstboot file
tells the Setup Agent application not to
run on subsequent reboots. To run it the next time the system
boots, remove /etc/sysconfig/firstboot
and execute chkconfig --level 5 firstboot
on.
The /etc/sysconfig/gpm file is used to
pass arguments to the gpm daemon at boot
time. The gpm daemon is the mouse server
which allows mouse acceleration and middle-click pasting. For more
information about what parameters are available for this file,
refer to the gpm man page. By default, the
DEVICE directive is set to /dev/input/mice.
The /etc/sysconfig/harddisks file
tunes the hard drive(s). An administrator can also use /etc/sysconfig/hardiskhd[a-h] to configure
parameters for specific drives.
 |
Warning |
| |
Do not make changes to this file without careful consideration.
By changing the default values, it is possible to corrupt all of
the data on the hard drive(s).
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The /etc/sysconfig/harddisks file may
contain the following:
-
USE_DMA=1, where setting this value to
1 enables DMA. However, with some chipsets and hard drive
combinations, DMA can cause data corruption. Check the hard drive documentation or with the
manufacturer before enabling this option. By default, this
entry is commented out, and therefore disabled.
-
Multiple_IO=16, where a setting of 16
allows for multiple sectors per I/O interrupt. When enabled, this
feature reduces operating system overhead by 30-50%. Use with caution. By default, this entry is
commented out, and therefore disabled.
-
EIDE_32BIT=3 enables (E)IDE 32-bit I/O
support to an interface card. By default, this entry is commented
out, and therefore disabled.
-
LOOKAHEAD=1 enables drive
read-lookahead. By default, this entry is commented out, and
therefore disabled.
-
EXTRA_PARAMS= specifies where extra
parameters can be added. By default, there are no parameters
listed.
The /etc/sysconfig/hwconf file lists
all the hardware that kudzu detected on
the system, as well as the drivers used, vendor ID, and device ID
information. The kudzu program detects and
configures new and/or changed hardware on a system. The /etc/sysconfig/hwconf file is not meant to be
manually edited. If edited, devices could suddenly show up as being
added or removed.
The /etc/sysconfig/i18n file sets the
default language, any supported languages, and the default system
font. For example:
LANG="en_US.UTF-8"
SUPPORTED="en_US.UTF-8:en_US:en"
SYSFONT="latarcyrheb-sun16"
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The /etc/sysconfig/init file controls
how the system appears and functions during the boot process.
The following values may be used:
-
BOOTUP=<value>, where <value> is one
of the following:
-
color — The standard color boot
display, where the success or failure of devices and services
starting up is shown in different colors.
-
verbose — An old style display
which provides more information than purely a message of success or
failure.
-
Anything else means a new display, but without
ANSI-formatting.
-
RES_COL=<value>, where <value> is the
number of the column of the screen to start status labels. The
default is set to 60.
-
MOVE_TO_COL=<value>, where <value> moves
the cursor to the value in the RES_COL
line via the echo -en command.
-
SETCOLOR_SUCCESS=<value>, where <value> sets
the success color via the echo -en
command. The default color is set to green.
-
SETCOLOR_FAILURE=<value>, where <value> sets
the failure color via the echo -en
command. The default color is set to red.
-
SETCOLOR_WARNING=<value>, where <value> sets
the warning color via the echo -en
command. The default color is set to yellow.
-
SETCOLOR_NORMAL=<value>, where <value> resets
the color to "normal" via the echo
-en.
-
LOGLEVEL=<value>, where <value> sets
the initial console logging level for the kernel. The default is 3;
8 means everything (including debugging), while 1 means only kernel
panics. The syslogd daemon overrides this
setting once started.
-
PROMPT=<value>, where <value> is one
of the following boolean values:
The /etc/sysconfig/ip6tables-config
file stores information used by the kernel to set up IPv6 packet
filtering at boot time or whenever the ip6tables service is started.
Do not modify this file by hand unless familiar with how to
construct ip6tables rules. Rules also can
be created manually using the /sbin/ip6tables command. Once created, add the rules
to the /etc/sysconfig/ip6tables file by
typing the following command:
/sbin/service ip6tables save
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Once this file exists, any firewall rules saved in it persists
through a system reboot or a service restart.
For more information on ip6tables,
refer to Chapter 18 iptables.
The /etc/sysconfig/iptables-config
file stores information used by the kernel to set up packet
filtering services at boot time or whenever the service is
started.
Do not modify this file by hand unless you are familiar with
constructing iptables rules. The easiest
way to add rules is to use the Security
Level Configuration Tool (system-config-securitylevel) application to create a
firewall. These applications automatically edit this file at the
end of the process.
Rules can also be created manually using the /sbin/iptables command. Once created, add the
rule(s) to the /etc/sysconfig/iptables
file by typing the following command:
/sbin/service iptables save
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Once this file exists, any firewall rules saved in it persists
through a system reboot or a service restart.
For more information on iptables, refer
to Chapter 18 iptables.
The /etc/sysconfig/irda file controls
how infrared devices on the system are configured at startup.
The following values may be used:
-
IRDA=<value>, where <value> is one
of the following boolean values:
-
yes — irattach runs and periodically checks to see if
anything is trying to connect to the infrared port, such as another
notebook computer trying to make a network connection. For infrared
devices to work on the system, this line must be set to yes.
-
no — irattach does not run, preventing infrared device
communication.
-
DEVICE=<value>, where <value> is the
device (usually a serial port) that handles infrared connections. A
sample serial device entry could be /dev/ttyS2.
-
DONGLE=<value>, where <value>
specifies the type of dongle being used for infrared communication.
This setting exists for people who use serial dongles rather than
real infrared ports. A dongle is a device that is attached to a
traditional serial port to communicate via infrared. This line is
commented out by default because notebooks with real infrared ports
are far more common than computers with add-on dongles. A sample
dongle entry could be actisys+.
-
DISCOVERY=<value>, where <value> is one
of the following boolean values:
-
yes — Starts irattach in discovery mode, meaning it actively
checks for other infrared devices. This must be turned on for the
machine to actively look for an infrared connection (meaning the
peer that does not initiate the connection).
-
no — Does not start irattach in discovery mode.
The /etc/sysconfig/keyboard file
controls the behavior of the keyboard. The following values may be
used:
-
KEYBOARDTYPE="sun|pc" where sun means a Sun keyboard is attached on /dev/kbd, or pc means a
PS/2 keyboard connected to a PS/2 port.
-
KEYTABLE="<file>", where <file> is the
name of a keytable file.
For example: KEYTABLE="us". The files
that can be used as keytables start in /lib/kbd/keymaps/i386 and branch into different
keyboard layouts from there, all labeled <file>.kmap.gz. The first file found
beneath /lib/kbd/keymaps/i386 that
matches the KEYTABLE setting is used.
The /etc/sysconfig/kuzdu file triggers
a safe probe of the system hardware by kudzu at boot time. A safe probe is one that
disables serial port probing.
The /etc/sysconfig/mouse file is used
to specify information about the available mouse. The following
values may be used:
-
FULLNAME="<value>", where "<value>"
refers to the full name of the kind of mouse being used.
-
MOUSETYPE="<value>", where "<value>" is
one of the following:
-
imps2 — A generic USB wheel
mouse.
-
microsoft — A Microsoft™ mouse.
-
mouseman — A MouseMan™ mouse.
-
mousesystems — A Mouse Systems™ mouse.
-
ps/2 — A PS/2 mouse.
-
msbm — A Microsoft™ bus mouse.
-
logibm — A Logitech™ bus mouse.
-
atibm — An ATI™ bus mouse.
-
logitech — A Logitech™ mouse.
-
mmseries — An older MouseMan™ mouse.
-
mmhittab — An mmhittab mouse.
-
XEMU3="<value>", where "<value>" is
one of the following boolean values:
-
yes — The mouse only has two
buttons, but three mouse buttons should be emulated.
-
no — The mouse already has three
buttons.
-
XMOUSETYPE="<value>", where "<value>"
refers to the kind of mouse used when X is running. The options
here are the same as the MOUSETYPE setting
in this same file.
-
DEVICE=<value>, where <value> is the mouse device.
A sample value, /dev/input/mice, is a
symbolic link that points to the actual mouse device.
The /etc/sysconfig/named file is used
to pass arguments to the named daemon at
boot time. The named daemon is a Domain Name System (DNS)
server which implements the Berkeley Internet
Name Domain (BIND) version 9
distribution. This server maintains a table of which hostnames are
associated with IP addresses on the network.
Currently, only the following values may be used:
-
ROOTDIR="</some/where>", where </some/where>
refers to the full directory path of a configured chroot
environment under which named runs. This
chroot environment must first be configured. Type info chroot for more information.
-
OPTIONS="<value>", where <value> is any
option listed in the man page for named
except -t. In place of -t, use the ROOTDIR line
above.
For more information about available parameters for this file,
refer to the named man page. For detailed
information on how to configure a BIND DNS server, refer to
Chapter 12 Berkeley Internet Name Domain
(BIND). By default, the file contains no parameters.
The /etc/sysconfig/netdump file is the
configuration file for the /etc/init.d/netdump service. The netdump service sends both oops data and memory
dumps over the network. In general, netdump is not a required service; only run it if
absolutely necessary. For more information about what parameters
are available for this file, refer to the netdump man page.
The /etc/sysconfig/network file is
used to specify information about the desired network
configuration. The following values may be used:
-
NETWORKING=<value>, where <value> is one
of the following boolean values:
-
HOSTNAME=<value>, where <value> should
be the Fully Qualified Domain Name
(FQDN), such as hostname.expample.com, but can be whatever hostname
is necessary.
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Note |
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For compatibility with older software that some users may need
to install, such as trn, the /etc/HOSTNAME file should contain the same value as
set here.
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-
GATEWAY=<value>, where <value> is the
IP address of the network's gateway.
-
GATEWAYDEV=<value>, where <value> is the
gateway device, such as eth0.
-
NISDOMAIN=<value>, where <value> is the
NIS domain name.
The /etc/sysconfig/ntpd file is used
to pass arguments to the ntpd daemon at
boot time. The ntpd daemon sets and
maintains the system clock to synchronize with an Internet standard
time server. It implements version 4 of the Network Time Protocol
(NTP). For more information about what parameters are available for
this file, use a Web browser to view the following file: /usr/share/doc/ntp-<version>/ntpd.htm (where
<version> is the version
number of ntpd). By default, this file
sets the owner of the ntpd process to the
user ntp.
The /etc/sysconfig/pcmcia file is used
to specify PCMCIA configuration information. The following values
may be used:
-
PCMCIA=<value>, where <value> is one
of the following:
-
PCIC=<value>, where <value> is one
of the following:
-
PCIC_OPTS=<value>, where <value> is the
socket driver (i82365 or tcic) timing parameters.
-
CORE_OPTS=<value>, where <value> is the
list of pcmcia_core options.
-
CARDMGR_OPTS=<value>, where <value> is the
list of options for the PCMCIA cardmgr
(such as -q for quiet mode, -m to look for loadable kernel modules in the
specified directory, and so on). Read the cardmgr man page for more information.
The /etc/sysconfig/radvd file is used
to pass arguments to the radvd daemon at
boot time. The radvd daemon listens for
router requests and sends router advertisements for the IP version
6 protocol. This service allows hosts on a network to dynamically
change their default routers based on these router advertisements.
For more information about available parameters for this file,
refer to the radvd man page. By default,
this file sets the owner of the radvd
process to the user radvd.
The /etc/sysconfig/rawdevices file is
used to configure raw device bindings, such as:
/dev/raw/raw1 /dev/sda1
/dev/raw/raw2 8 5
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The /etc/sysconfig/samba file is used
to pass arguments to the smbd and the
nmbd daemons at boot time. The smbd daemon offers file sharing connectivity for
Windows clients on the network. The nmbd
daemon offers NetBIOS over IP naming services. For more information
about what parameters are available for this file, refer to the
smbd man page. By default, this file sets
smbd and nmbd to
run in daemon mode.
The /etc/sysconfig/selinux file
contains the basic configuration options for SELinux. This file is
a symbolic link to /etc/selinux/config.
For more information on SELinux, refer to Chapter 21 SELinux.
The /etc/sysconfig/sendmail file
allows messages to be sent to one or more clients, routing the
messages over whatever networks are necessary. The file sets the
default values for the Sendmail application to run. Its default
values are set to run as a background daemon and to check its queue
each hour in case something has backed up.
Values include:
-
DAEMON=<value>, where <value> is one
of the following:
-
yes — Sendmail should be
configured to listen to port 25 for incoming mail. yes implies the use of Sendmail's -bd options.
-
no — Sendmail should not be
configured to listen to port 25 for incoming mail.
-
QUEUE=1h which is given to Sendmail as
-q$QUEUE. The -q
option is not given to Sendmail if /etc/sysconfig/sendmail exists and QUEUE is empty or undefined.
The /etc/sysconfig/spamassassin file
is used to pass arguments to the spamd
daemon (a daemonized version of Spamassassin) at boot time.
Spamassassin is an email spam filter application. For a list of
available options, refer to the spamd man
page. By default, it configures spamd to
run in daemon mode, create user preferences, and auto-create
whitelists (allowed bulk senders).
For more information about Spamassassin, refer to Section 11.4.2.6 Spam
Filters.
The /etc/sysconfig/squid file is used
to pass arguments to the squid daemon at
boot time. The squid daemon is a proxy
caching server for Web client applications. For more information on
configuring a squid proxy server, use a
Web browser to open the /usr/share/doc/squid-<version>/ directory (replace
<version> with the squid version number installed on the system). By
default, this file sets squid to start in
daemon mode and sets the amount of time before it shuts itself
down.
The /etc/sysconfig/system-config-securitylevel file
contains all options chosen by the user the last time the Security Level Configuration Tool (system-config-securitylevel) was run. Users should
not modify this file by hand. For more information about the
Security Level Configuration Tool, refer
to the chapter titled Basic Firewall
Configuration in the Red Hat Enterprise
Linux System Administration Guide.
The /etc/sysconfig/system-config-users
file is the configuration file for the graphical application,
User Manager. This file is used to
filter out system users such as root,
daemon, or lp.
This file is edited by the =>
pull-down
menu in the User Manager application and
should never be edited by hand. For more information on using this
application, refer to the chapter called User
and Group Configuration in the Red Hat
Enterprise Linux System Administration Guide.
The /etc/sysconfig/system-logviewer
file is the configuration file for the graphical, interactive log
viewing application, Log Viewer. This
file is edited by the => pull-down menu in the Log Viewer application and should not be edited
by hand. For more information on using this application, refer to
the chapter called Log Files in the
Red Hat Enterprise Linux System Administration
Guide.
The /etc/sysconfig/tux file is the
configuration file for the Red Hat Content Accelerator (formerly
known as TUX), the kernel-based Web server. For more information on
configuring the Red Hat Content Accelerator, use a Web browser to
open the /usr/share/doc/tux-<version>/tux/index.html file
(replace <version> with the
version number of TUX installed on the system). The parameters
available for this file are listed in /usr/share/doc/tux-<version>/tux/parameters.html.
The /etc/sysconfig/vncservers file
configures the way the Virtual Network
Computing (VNC) server starts up.
VNC is a remote display system which allows users to view the
desktop environment not only on the machine where it is running but
across different networks on a variety of architectures.
It may contain the following:
-
VNCSERVERS=<value>, where <value> is set
to something like "1:fred", to indicate
that a VNC server should be started for user fred on display :1.
User fred must have set a VNC password using the vncpasswd command before attempting to connect to
the remote VNC server.
Note that when using a VNC server, communication with it is
unencrypted and it should not be used on an untrusted network. For
specific instructions concerning the use of SSH to secure VNC
communication, read the information found online at https://www.uk.research.att.com/archive/vnc/sshvnc.html.
To find out more about SSH, refer to Chapter
20 SSH Protocol in the Red Hat
Enterprise Linux System Administration Guide.
The /etc/sysconfig/xinetd file is used
to pass arguments to the xinetd daemon at
boot time. The xinetd daemon starts
programs that provide Internet services when a request to the port
for that service is received. For more information about available
parameters for this file, refer to the xinetd man page. For more information on the
xinetd service, refer to Section 17.3 xinetd.
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