Troubleshooting. If you are having problems with a sound card, a manual configuration is an option. Here is my setup for a SoundBlaster16-compatibile ("no name") soundcard that persistently played at half speed (too slow and with "low voice") because it was misdetected. The resource to read turned out to be: /usr/src/linux-xxx/Documentation/sound (hope you installed the kernel source code so that you have the documentation). The file to edit is /etc/modules.conf. The critical line in this file (after manual edition) is:
options sb esstype=1688 io=0x220 irq=5 dma=0 dma16=5 mpu_io=0x330
The change that I had to make was to insert the "esstype=" option. After modification, the best to test your setup is to cold reboot (shutdown to a halt, and then recycle the power).
| : | Field separator (separates the entries in the file). |
| \ | (at the end of line) Continuation on the next line. |
| lp | Name of the printer. "lp" is the name of the default printer on your machine. Subsequent printers are often, by default, given the the names lp0 or lp1, ... (or whatever you like) but this should not be confused with the name of the devices (parallel ports) to which they are connected. |
| sd=/var/spool/lpd/lp | My spool directory (sd). |
| mx#0 | Maximum size of print jobs (mx) in blocks. "0" means no limit. |
| sh | I want headers to be suppressed (sh). Header is the page with your name that prints before your printing job (waste of paper if you print at home). |
| rm=mars | Name of the remote machine (rm), which on my system is called "mars (my printer is connected to a different computer). |
| rp=lp
or lp=/dev/lp0 |
Name of the remote printer (rp), which is the name of the printer
on the remote machine ("lp" on "mars" on my home network) or the name of the device on the local machine. "/dev/lp0" is the first parallel port on RH6.x (it used to be /dev/lp1 on RH5.2, the numbering of parallel ports changed). |
| if=/var/spool/lpd/lp/filter | Input filter (if). Your printing job will be formatted by this "filter" before it is sent to the printer. |
| sf | Suppress the form feed (sf) that is normally sent when printing is completed (use it if your printer keeps printing an empty page at the end of each jobs). |
Most printers will work perfectly under Linux, but some may not utilize their full capablity due to lack of information/drivers from the vendors. Therefore, when purchasing a new printer, you may want to consult the database of Linux printers: http://www.linuxprinting.org/database.html. In brief, it is a good bet is to select ( http://www.linuxprinting.org/suggested.html):
- For inexpensive colour printing: an Epson Stylus, for example:
Stylus C80 (better) or Stylus C60 (cheaper) (Dec.2001). HP inkjets are generally
less recommended than Epson's. Please note that "inkjet-type" printers are
(in general) "not-so-great" for black-and-white printing. Also, they are
meant to be "personal" printers and do not handle well high volumes. Yet
they can offer excellent colour output, particularly on good quality paper.
Kids love inkjets.
- For low-end laser printing: a Lexmark or Brother printer.
Many Hewlett-Packard (HP) laser printers will also work perfectly, but one
has to be more careful when selecting an HP printer due to their more limited
support. Lower-cost laser printers are always black-and-white, but they
offer excellent quality text printouts. You may avoid some headaches if
you select a printer which supports "Postscript".
Here is a listing of some system-wide configuration files that I use most often:
SHELL DEFAULTS
/etc/bashrc - system-wide default functions and aliases for the
bash shell
/etc/profile - system-wide defaults for bash shell, including
system-wide environment variables.
ADMINISTRATIVE SETTINGS
/etc/passwd - contains passwords and other information concerning
users who are registered to use the system. It can be modified by root directly,
but it is preferable to use a configuration utility such as passwd to make
the changes. A corrupt /etc/passwd file can easily render a Linux box unusable.
/etc/shadow - contains "shadow" information for the passwd file,
i.e., the information pieces which "the world" does not have permission
to read.
/etc/group - similar to /etc/passwd but for groups.
/etc/crontab - setup for "cron", which runs commands periodically
(hourly, daily, weekly, monthly, etc.).
/etc/inittab - runs different programs and processes on startup.
/etc/issue - message that accompanies login prompt. This is often
overwitten by the rc.local script.
/etc/issue.net - same as above, but used when login is attempted
over the network.
/etc/motd - "message of the day" file, displayed after a user
logs in.
/etc/rc.d/rc.local - the last script to execute on the system
bootup. I put the commands which customize my local machine at the end of
this file. It works like DOS "autoexec.bat".
NETWORK CONFIGURATION
/etc/hosts - contains a list of host names and absolute IP addresses.
/etc/hosts.allow - hosts allowed to access Internet services
/etc/hosts.deny - hosts forbidden to access Internet services
/etc/resolv.conf - setups for a list of domain name servers used
by the local machine
/etc/inetd.conf - configures the inetd daemon to tell it what
TCP/IP services your machine should run.
/etc/exports - specifies hosts to which file systems can be exported
using NFS (network file system). man exports contains information
on how to set up this file for remote users.
HARDWARE CONFIGURATION
/etc/conf.modules - setup for the linux kernel modules. Modules
are like "device drivers" under MS Windows or DOS.
/etc/fstab - contains information on partitions and filesystems
used by system to mount different partitions and devices on the directory
tree.
/etc/mtab - shows currently mounted devices and partitions and
their status.
/etc/lilo.conf - configuration file for lilo boot loader.
/boot/grub/grub.conf - configuration file for grub boot
loader.
/etc/printcap - setup for printers.
/etc/termcap - ASCII database defining the capabilities and characteristics
of different consoles, terminals, and printers. You typically don't want
to change these.
/etc/X11/XF86Config - X configuration file. For XFree version
4.xx, the file is /etc/X11/XF86Config-4 (if it does not exist,
then XF86Config is tried).
ls -l /dev/ttyS3
on my system produces the following output:
crwxr-xr-x 1 root tty 4, 67 Mar 13 22:59 ttyS3
The initial "c" indicates a character device. "b" would mean "block device",
"p"=FIFO device, "u"=unbuffered character device, "d"=directory, "l"=symbolic
link. The numbers "4, 67" mean that the device major number is 4 and the
minor number is 67. To make some devices usable to all users on your system,
you may need to set the proper permissions. For example:
ls -l /dev/usb/scanner0
chmod 666 /dev/usb/scanner0
Here is a list of some common devices:
/dev/ttyS0 - the first serial port. The mouse is typically connected
here.
/dev/ttyS1 - the second serial port. This may well be the device
to which your modem is connected.
/dev/ttyS2 and /dev/ttyS3 the third and fourth
serial port (typically not present, but your internal modem may well be
configured as one of these).
/dev/modem - the serial modem. In the typical case, a symbolic
link to /dev/ttyS1, /dev/ttyS2, /dev/ttyS3 or /dev/ttyS0, depending to which
serial port your modem is connected.
/dev/mouse - mouse. In the typical case, a symbolic link to /dev/ttyS0
or similar (see above), depending to which serial port your mouse is connected.
/dev/lp0 - printer on the first parallel port. That's where
normally printers are connected.
/dev/lp1 - printer on the second parallel port (typically
not present).
/dev/fd0 - first floppy disk drive (almost always present).
/dev/fd0H1440 - driver for the first floppy drive in the high-density
mode (1440 kB). Generally, this (or a driver with a device with a similar
descriptive name) is invoked when formatting a floppy drive to a particular
density. Slackware also comes with drivers that allow for formatting a 3.5"
diskette with up to 1.7MB of space. Red Hat and Mandrake do not contain
these device drivers files by default.
/dev/fd1 - second floppy disk drive.
/dev/hda - first IDE hard drive (whole drive). Most hard
drives on IBM-compatibile PCs are IDE.
/dev/hdb - second IDE hard drive (whole drive). On many computers,
the IDE cdrom drive is attached here.
/dev/hdc - third IDE drive (whole drive). On many computers, the
IDE cdrom drive is attached here.
/dev/cdrom - a symbolic link to the appropriate drive interface,
typically /dev/hdc or /dev/hdb (a CDROM) or /dev/scd0 (a CD-R/RW writer).
/dev/hda1 - the first partition on the first IDE hard drive. /dev/hda2
is the second partion on the first IDE hard drive. As one could guess, /dev/hdd8
would be the eight partition on the fourth IDE hard drive.
/dev/tty1 - the first text console. /dev/tty2 is the
second text console, etc.
/dev/dsp - digital audio, i.e., the sound card. "dsp" stands for
"digital signal processing".
/dev/sndstat - do cat /dev/sndstat to learn about the
status of your sound devices.
/dev/null - used when you want to send output into oblivion.
/dev/random - used to read pseudo-random numbers. Do cat /dev/random
to display garbage-looking characters on your screen. There is also /dev/urandom
to generate lower-quality random sequences.
/dev/sda -the first SCSI drive (whole drive). On a home machine,
you are unlikely to have any SCSI drives (expensive).
/dev/sdb - the second scsi drive ("sdc" is the third scsi drive,
etc. There can be many scsi drive on a system).
/dev/sda1 - the first partition on the first scsi drive.
/dev/sr0 - the first scsi CD drive (sometimes called /dev/scd0).
If you have an ATAPI CD writer, it will also be likely here.
/dev/sr1-is the second scsi CD drive (sometimes called /dev/scd1),
(/dev/sr2 is the third scsi CD drive, etc. There can be many scsi
CD drives on the system).
/dev/usb/scanner0 - a usb scanner. Try: less /usr/src/linux/Documentation/usb/scanner.txt
for an info on scanner configuration from scratch.
For more info try:
less /usr/src/linux/Documentation/devices.txt
man MAKEDEV
As explained in /usr/src/linux/Documentation/devices.txt, I may need to create some symbolic links to device files locally to configure my system. This is merely a tabulation of existing practice, and does not constitute a recommendation. However, if the links exist, they should have the following uses:
/dev/mouse Current mouse port***
/dev/tape Current tape device
/dev/cdrom Current CD-ROM device***
/dev/cdwriter Current CD-writer device (but my RedHat
have /dev/cdrecorder)
/dev/scanner Current scanner device
/dev/modem Current dialout (modem) port***
/dev/root Current root filesystem
/dev/swap Current swap device
The *** mark the symbolic links that are surely present on my Mandrake
system. For example, if having problems with mouse I would do something
like (as root):
ls -l /dev/mouse
[see if the mouse device is present and where it points]
ln -s /dev/ttyS0 /dev/mouse
[create a symbolic link so that /dev/mouse point to the first serial port]
For SCSI (and ATAPI) devices, /dev/tape and /dev/cdrom should point to the ``cooked'' devices (/dev/st* and /dev/sr*, respectively), whereas /dev/cdwriter and /dev/scanner should point to the appropriate generic SCSI devices (/dev/sg*).
Non-transient sockets and named pipes may exist in /dev. Common entries
are:
/dev/printer socket lpd local
socket
/dev/log socket
syslog local socket
/dev/gpmdata socket gpm mouse
multiplexer
Here is a short list of popular daemons with a brief description:
anacron - checks `cron' jobs that were left out due to down time
and executes them. Useful if you have cron jobs scheduled but don't run
your machine all the time--anacron will detect that during bootup.
amd - automount daemon (automatically mounts removable media).
apmd - Advanced Power Management BIOS daemon. For use on machines,
especially laptops, that support apm.
arpwatch - keeps watch for ethernet/ip address pairings.
atd - runs jobs queued by the "at" command.
autofs - control the operation of automount daemons (competition
to amd).
bootparamd - server process that provides information to diskless
clients necessary for booting.
crond - automatic task scheduler. Manages the execution of tasks
that are executed at regular but infrequent intervals, such as rotating
log files, cleaning up /tmp directories, etc.
cupsd - the Common UNIX Printing System (CUPS) daemon. CUPS is
an advanced printer spooling system which allows setting of printer options
and automatic availability of a printer configured on one server in the
whole network. The default printing system of Linux Mandrake.
dhcpd - implements the Dynamic Host Configuration Protocol (DHCP)
and the Internet Bootstrap Protocol (BOOTP).
gated - routing daemon that handles multiple routing protocols
and replaces routed and egpup.
gpm - useful mouse server for applications running on the Linux
text console.
httpd - daemon for the Apache webserver.
inetd - listens for service requests on network connections, particularly
dial-in services. This daemon can automatically load and unload other daemons
(ftpd, telnetd, etc.), thereby economizing on system resources. Newer systems
use xinetd instead.
isdn4linux - for users of ISDN cards.
kerneld - automatically loads and unloads kernel modules.
klogd - the daemon that intercepts and displays/logs the kernel
messages depending on the priority level of the messages. The priority is
(copied from /usr/include/linux/kernel.h ):
KERN_EMERG "<0>"
system is unusable
KERN_ALERT "<1>"
action must be taken immediately
KERN_CRIT "<2>"
critical conditions
KERN_ERR
"<3>" error conditions
KERN_WARNING "<4>" warning
condition
KERN_NOTICE "<5>"
normal but significant condition
KERN_INFO "<6>"
informational
KERN_DEBUG "<7>"
debug-level messages
The messages typically go to the appropriately named files in the directory
/var/log/kernel.
kudzu - detects and configures new or changed hardware during
boot.
keytable - loads selected keyboard map.
linuxconf - the linuxconf configuration tool. The automated part
is run if you want linuxconf to perform various tasks at boottime to maintain
the system configuration.
lpd - printing daemon.
mcserv - server program for the Midnight Commander networking
file system. It provides access to the host file system to clients running
the Midnight file system (currently, only the Midnight Commander file manager).
If the program is run as root the program will try to get a reserved port
otherwise it will use 9876 as the port. If the system has a portmapper running,
then the port will be registered with the portmapper and thus clients will
automatically connect to the right port. If the system does not have a portmapper,
then a port should be manually specified with the -p option (see below).
named - the Internet Domain Name Server (DNS) daemon.
netfs - network filesystem mounter. Used for mounting nfs, smb
and ncp shares on boot.
network -activates all network interfaces at boot time by calling
scripts in /etc/sysconfig/network-scripts .
nfsd - used for exporting nfs shares when requested by remote
systems.
nfslock - starts and stops nfs file locking service.
numlock - locks numlock key at init runlevel change.
pcmcia - generic services for pcmcia cards in laptops.
portmap - needed for Remote Procedure Calls. Most likely, you
need it for running network.
postfix - mail transport agent which is a replacement for sendmail.
Now the default on desktop installations of Mandrake (RedHat uses sendmail
instead).
random - saves and restores the "entropy" pool for higher quality
random number generation.
routed - daemon that manages routing tables.
rstatd - kernel statistics server.
rusersd, rwalld - identification of users and "wall"
messaging services for remote users.
rwhod - server which maintains the database used by the rwho(1)
and ruptime(1) programs. Its operation depends on the ability to broadcast
messages on a network.
sendmail - mail transfer agent. This is the agent that comes with
Red Hat.
smbd - the SAMBA (or smb) daemon, a network connectivity
services to MS Windows computers on your network (hard drive sharing, printers,
etc).
squid - An http proxy with caching. Proxies relay requests from
clients to the outside world, and return the results. You would use this
particular proxy if you wanted to use your linux computer as a gateway to
the Internet for other computer on your network. Another (and probably safer
at home) way to do it, is to set up masquarading.
syslogd - manages system activity logging. The configuration file
is /etc/syslog.conf .
smtpd - Simple Mail Transfer Protocol, designed for the exchange
of electronic mail messages. Several daemons that support SMTP are available,
including sendmail, smtpd, rsmtpd, qmail, zmail, etc.
usb - daemon for devices on Universal Serial Bus.
xfs - X font server.
xntpd - finds the server for a NIS domain and stores the information
about it in a binding file.
ypbind - NIS binder. Needed if computer is part of Network Information
Service domain.
Go to Part: 4.5 - Networking