The following information outlines some of the various files in /etc/sysconfig, their function, and their contents. This information 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.
Files in /etc/sysconfig
The following files are normally found in /etc/sysconfig:
It is possible that your system may be missing a few of them if the corresponding program that would need that file is not installed.
Next, we will take a look at each one.
The /etc/sysconfig/amd file contains various parameters used by amd allowing for the automounting and automatic unmounting of filesystems.
The /etc/sysconfig/apmd file is used by apmd as a configuration for what things to start/stop/change on suspend or resume. It is set up to turn on or off apmd during startup, depending on whether your hardware supports Advanced Power Management (APM) or if you choose not to use it. apm is a monitoring daemon that works with power management code within the Linux kernel. It can alert you to a low battery if you are using Red Hat Linux on a laptop, among other things.
The /etc/sysconfig/authconfig file sets the kind of authorization to be used on the host. It contains one or more of the following lines:
yes — MD5 is used for authentication.
no — MD5 is not used for authentication.
yes — Kerberos is used for authentication.
no — Kerberos is not used for authentication.
yes — LDAP is used for authentication.
no — LDAP is not used for authentication.
The /etc/sysconfig/clock file controls the interpretation of values read from the system clock. Earlier releases of Red Hat Linux used the following values (which are deprecated):
GMT — Indicates that the clock is set to Universal Time (Greenwich Mean Time).
ARC — Indicates the ARC console's 42-year time offset is in effect (for Alpha-based systems only).
Currently, the correct values are:
true — Indicates that the clock is set to Universal Time. Any other value indicates that it is set to local time.
true — Indicates the ARC console's 42-year time offset is in effect. Any other value indicates that the normal UNIX epoch is assumed (for Alpha-based systems only).
The /etc/sysconfig/desktop file specifies the desktop manager to be run, such as:
The /etc/sysconfig/firewall file contains various firewall settings. By default, this file (if created) is empty.
The /etc/sysconfig/harddisks file allows you to tune your hard drive(s). You can also use /etc/sysconfig/hardiskhd[a-h], to configure parameters for specific drives.
Do not make changes to this file lightly. If you change the default values stored here, you could corrupt all of the data on your hard drive(s).
The /etc/sysconfig/harddisks file may contain the following:
USE_DMA=1, where setting this to 1 enables DMA. However, with some chipsets and hard drive combinations, DMA can cause data corruption. Check with your hard drive documentation or manufacturer before enabling this.
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.
EIDE_32BIT=3 enables (E)IDE 32-bit I/O support to an interface card.
LOOKAHEAD=1 enables drive read-lookahead.
EXTRA_PARAMS= specifies where extra parameters can be added.
The /etc/sysconfig/hwconf file lists all the hardware that kudzu detected on your 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 you do edit it, devices could suddenly show up as being added or removed.
The /etc/sysconfig/i18n file sets the default language, such as:
The /etc/sysconfig/init file controls how the system will appear and function during bootup.
The following values may be used:
BOOTUP=color means the standard color boot display, where the success or failure of devices and services starting up is shown in different colors.
BOOTUP=verbose means 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.
yes — Enables the key check for interactive mode.
no — Disables the key check for interactive mode.
The /etc/sysconfig/ipchains file contains information used by the kernel to set up ipchains rules regarding packet filtering.
This file is modified by running the service ipchains save command when valid ipchains rules are in place. You should not manually edit this file. Instead, use the ipchains command to configure the necessary packet filtering rules and then save the rules to this file.
Like /etc/sysconfig/ipchains, the /etc/sysconfig/iptables file stores information used by the kernel to provide specialized packet filtering services. However, this file is used by iptables rather than ipchains.
You should not modify this file by hand unless you are familiar with methods used to construct iptables rules. These rules are written to /etc/sysconfig/iptables by the service iptables save command, which stores the current iptables rules by running the /sbin/iptables-save program. Then, when iptables is restarted, such as is the case when the system is booted, the /sbin/iptables-restore program reads the file and reinstitutes the packet filtering rules.
The /etc/sysconfig/irda file controls how infrared devices on your system are configured at startup.
The following values may be used:
yes — irattach will be run, which 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 your system, this line must be set to yes.
no — irattach will not be run, preventing infrared device communication.
yes — Starts irattach in discovery mode, meaning it actively checks for other infrared devices. This needs to be turned on for the machine to be actively looking 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, which is used on SPARCs only. sun means a Sun keyboard is attached on /dev/kbd, and pc means a PS/2 keyboard connected to a PS/2 port.
The /etc/sysconfig/kuzdu allows you to specify a safe probe of your system's hardware by kudzu at boot time. A safe probe is one that disables serial port probing.
yes — kuzdu does a safe probe.
no — kuzdu does a normal probe.
The /etc/sysconfig/mouse file is used to specify information about the available mouse. The following values may be used:
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.
yes — The mouse only has two buttons, but three mouse buttons should be emulated.
no — The mouse already has three buttons.
In addition, /dev/mouse is a symbolic link that points to the actual mouse device.
The /etc/sysconfig/network file is used to specify information about the desired network configuration. The following values may be used:
yes — Networking should be configured.
no — Networking should not be configured.
For compatibility with older software that people might install (such as trn), the /etc/HOSTNAME file should contain the same value as here.
The /etc/sysconfig/pcmcia file is used to specify PCMCIA configuration information. The following values may be used:
yes — PCMCIA support should be enabled.
no — PCMCIA support should not be enabled.
i82365 — The computer has an i82365-style PCMCIA socket chipset.
tcic — The computer has a tcic-style PCMCIA socket chipset.
The /etc/sysconfig/rawdevices file is used to configure raw device bindings, such as:
/dev/raw/raw1 /dev/sda1/dev/raw/raw2 8 5
The /etc/sysconfig/sendmail file allows messages to be sent to one or more recipients, routing the message over whatever networks are necessary. The file sets the default values for the Sendmail application to run. Its default values are to run as a background daemon, and to check its queue once an hour in case something has backed up.
The following values may be used:
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/soundcard file is generated by sndconfig and should not be modified. The sole use of this file is to determine what card entry in the menu to pop up by default the next time sndconfig is run. Soundcard configuration information is located in the /etc/modules.conf file.
It may contain the following:
The /etc/sysconfig/ups file is used to specify information about any Uninterruptible Power Supplies (UPS) connected to your system. A UPS can be very valuable for a Red Hat Linux system because it gives you time to correctly shut down the system in the case of power interruption. The following values may be used:
yes — A UPS device is connected to your system.
no — A UPS device is not connected to your system.
apcsmart — For a APC SmartUPS™ or similar device.
fentonups — For a Fenton UPS™.
optiups — For an OPTI-UPS™ device.
bestups — For a Best Power™ UPS.
genericups — For a generic brand UPS.
ups-trust425+625 — For a Trust™ UPS.
The /etc/sysconfig/vncservers file configures how the Virtual Network Computing (VNC) server starts up. VNC is a remote display system which allows you to view a desktop environment not only on the machine where it is running but across different networks (from a LAN to the Internet) and using a wide variety of machine architectures.
It may contain the following:
Note that when you use a VNC server, your communication with it is unencrypted, and so it should not be used on an untrusted network. For specific instructions concerning the use of SSH to secure the VNC communication, please read the information found at http://www.uk.research.att.com/vnc/sshvnc.html. To find out more about SSH, see Chapter 10 or Official Red Hat Linux Customization Guide.