Debian Tips in
filesystems,boot,security,graphics and storage devices
How to convert
existing ext2 partition to ext3?
Ext3 is a journaling file systems, and you can look at it as
ext2 plus journalling. First create a journal for your file
system using, tune2fs -j /dev/hdaX You can do this on a mounted
or an unmounted filesystem. If you create the journal on a
mounted filesystem you will see a .journal file. Do not try to
access this journal file.
You can now edit your /etc/fstab to change 'ext2' to 'ext3' or
mount your filesystem as ext3 using,mount -t ext3 /dev/hdaX /mnt/
With mke2fs -j /dev/hdaX you can format a raw partition as ext3.
You can then mount this as ext2 as well. Just check if you have
the line ext3 in the file /etc/mkinitrd/modules.
How to convert ext3 partition back to
You can just change your mount type as 'ext2'. But if you really
want to make it a 'ext2', unmount the file system and do,
tune2fs -O ^has_journal /dev/hdaX Force an fsck to be on the
safer,fsck.ext2 -f /dev/hdaX Get rid of the .journal file, as
that doesn't do any purpose now.
How to setup /etc/vfstab
file for the ext3 file system ?
Instead of just specifying the new file system as ext3, enter it
as "ext3, ext2". This instructs the kernel to first try mounting
as ext3. If that doesn't work for any reason, it gets mounted as
ext2 (atleast!). For fsck to understand this convention, you
must make a link in /sbin/ext3,ext2 to /sbin/ext2. This may
sound ugly - but there is no other way.
How to avoid fsck prompts during the
Write 'FSCKFIX=yes' in /etc/default/rcS. You will not face the
fsck problem from the next reboot onwards. However, if the disk
is corrupted very badly, your presence may be required. I had
done some kernel tweaks also for that. I will write about
in subsequent tips.
How to mount my windows
share on Linux using samba?
Have this line in your /etc/fstab //Server/ShareName
/home/ServerShare smb username=user,password=password 1 2
This would work in a home environment, where you don't mind
putting the password in fstab file. If you want to be cautious,
have a script ask for your password and mount the stuff using
smbmount command. However, if you like to do this as non-root,
specify the mount point option in /etc/fstab alongwith noauto
and user options.
If you get annoyed, when you accidentally rebooted the system by
pressing the three magic keys, comment out this line in /etc/inittab
as,ca::ctrlaltdel:/sbin/shutdown -t3 -r now You may
alternatively allow specific users with this capability by
changing the line as below and adding the specific login ids in
'/etc/shutdown.allow',ca::ctrlaltdel:/sbin/shutdown -a -t3 -r
fluded with messages during Error messages on the console screen
By default /etc/syslog.conf is set to overwrite the console
screen. Edit the last (or appropriate) part of this file to
change this behaviour.You may also run "dmesg -n1" to quiet
on-screen error messages.
I cannot boot the system
No problem, even if you didn't bother to make a boot disk during
install. If lilo is broken, grab the boot disk from the Debian
installation set and boot your system from it. At the boot
prompt, assuming the root partition of your Linux installation
is on /dev/hda12 and you want runlevel 3, enter:
boot: rescue root=/dev/hda2 3
Then you are booted into an almost fully
functional system using the kernel on the floppy. There may be
minor glitches due to lack of kernel features or modules.
Debian PC doesn't power-off
on shutting down?
Well, you are not a lone user coming to this
problem. Make sure of all these things first-
• Check your motherboard for APM support
• Your kernel is compiled with the APM support and the
'real-mode flag' is enabled
• For 2.2 kernels add the "apm=on" flag in the /etc/lilo.conf
(for append="" secion) or pass at the boot time
• For SMP kernels add the "apm=power-off" also in /etc/lilo.conf
or pass at the boot time
• For 2.4 kernels, do "insmod apm power_off=1"
• Use the appropriate command like poweroff or shutdown -h to
shutdown your system. If you use ctr-alt-del on the command
line, change the line in /etc/inittab to begin with 'ca:'
• If you still can't make it work, try using ACPI instead of APM
(only for 2.4 kernels). ACPI does not need any other boot
How to add have my own file
get executed during the boot sequence?
Create the file in /etc/init.d/, give
executable permissions and run "update-rc.d" with appropriate
arguments to create the links from various run levels.
How do configure (add or
delete) start-up services on debian?
Use "rcconf" and unselect or deselect your
Having trouble in setting
your system time?
Most probably you are not running the 'hwclock'
after changing the date. Do this sequence,date MMDDhhmmCCYY;
hwclock --utc; hwclock --systohc; hwclock --show Alternatively,
if you have internet connection do a ntpdate <server>
Do you know of make
If you just applied a patch to your kernel and
would like to use the newly added options, this option is very
useful if you don't want to spend an hour hitting Enter through
all your settings. oldconfig will take current settings as
defaults, and prompts for any new options that may have appeared
in this version of the kernel.
How to set default compiler
options for gcc, for all the programs you compile on your
Have these lines in your ~/.bash_profile or
/etc/profile as per your needs.
export CFLAGS=" -O3 -march=i686 -mcpu=i686"
export CXXFLAGS=$CFLAGS (for C++ stuff to compile with the same
How to make use of my "windoze"
keys on my keyboard?
Add these lines in your ~/.Xmodmap file:
keycode 115 = F13
keycode 116 = F14
keycode 117 = F15
Now add the following line to .xsession: modmap ~/.Xmodmap.
Restart your window manager and now your F13, F14 and F15 keys
represent the left-Win key, right-Win-key and context-menu key.
How to have the special
multimedia keys on my keyboard get working in X?
Lot of the newer keyboards like Microsoft
Natural Pro have lot of multimedia keys, which can be
programmed. You can either create Xmodmap entries for the keys
if you know the keyboard configuration or use the hotkeys
package (.deb available).
How to transform the "\n" character
between Unix and Msdos formats?
Use "flip" (apt-get install flip, if you don't
have it already). You may use this on text or binary files.
A tip on your system security, consider removing "/etc/hosts.equiv"
This file allows other hosts to be trusted by your system. It
can be used to log on to your machine without a password. If you
are not running "r" commands, you should have no use for this
file and it should be removed. Also, disable 'r' programs like
rlogin, rsh and use ssh and scp.
How to look at the log files for 'su'
grep "su.*-root" /var/log/auth.log
Can't play the audio
CD while logged into Gnome as user, since only root can mount
If you have 'linuxconf' installed, select the drive you want to
access in the 'Access local drive' section. In the Options tab
select the User Mountable option. Alternatively, give mount
permissions to the user in /etc/fstab as - (add 'user' in the
/dev/cdrom /mnt/cdrom iso9660
user,exec,dev,ro,noauto 0 0
Why don't I see long
filenames of my Windows CD-ROM on Linux?
If you can see the long filenames of your
cd-rom under Windows but not under Linux, it may be formatted
using Microsoft's proprietary Joliet filesystem. It allows for
long filenames encoded using the 16-bit UNICODE format. You just
need to enable the flag for 'Microsoft Joliet file system
extensions' in your kernel configuration. If you want to display
filenames with native language characters from Joliet CD-ROMs
correctly on the screen, you need to enable support in the
kernel for the appropriate NLS ISO8859 character sets.
How to read the volume
label of my CD-ROM?
You may either use the utility called volname
dd if=/dev/hdc bs=1 skip=32808 count=32 (use appropriate device
How can I tell the speed of
my CD-ROM device?
This is only an approximate way of telling:
This command measures how long is takes to read 3000K of data
time -p dd if=/dev/cdrom of=/dev/null bs=1k count=3000
3000+0 records in
3000+0 records out
The transfer rate of single speed drives is 150 kilobytes per
second, which should take about 10 seconds. At double speed it
would take five seconds, quad speed would take 2.5, etc. The
"real" time above is probably the best number to look at -- in
this case it indicates a double speed drive. For better results,
increase the amount of data or run multiple iterarion for a
better approximate value.
Want to duplicate a VCD
from another VCD?
cdrdao read-cd --paranoia-mode 2 --read-raw
--driver generic-mmc --device 0,0,0 data.toc
How do I get my CD-Recorder
(CD-RW) get to work?
Scan for CD Recorders on your system with
cdparanoia -Qsv once. This might give any information on the
available CD recorders on the system. Also read the man pages of
cdrecord, mkisofs, cdda2wav, cdparanoia.
• Make sure that the modules sg and ide-scsi
are installed in the kernel with modconf or insmod. Also have
these files available on your system: cdrecord, mkisofs,
cdda2wav or cdparanoia
• If SCSI device, add or edit this into /etc/lilo.conf append =
"idebas=33 hdd=ide-scsi max_scsi_luns=1. Run lilo once.
• create the directory /cdrw
• Edit your /etc/fstab to mount the device (scd0 or hdd) to /cdrw
• Create any synbolic links to, /dev/cdrw
• cdrecord -scanbus and verify