Webmin is a web-based interface for system administration for Unix. Using any browser that supports tables and forms (and Java for the File Manager module), you can setup user accounts, Apache, DNS, file sharing and so on.
Webmin consists of a simple web server, and a number of CGI programs which directly update system files like /etc/inetd.conf and /etc/passwd. The web server and all CGI programs are written in Perl version 5, and use no non-standard Perl modules.
download webmin from this site
http://www.webmin.com/download.html
install it
#dpkg -i webmin_1.441_all.deb
You should now be able to login to Webmin at the URL https://localhost:10000/
Webmin User Password Change
If you want to change root password in webmin use this included Perl script:
sudo /usr/share/webmin/changepass.pl /etc/webmin root
If you want to install any standard modules you can download from
http://www.webmin.com/standard.html
If you want to install third party modules you can download from
http://www.webmin.com/third.html
Monday, January 26, 2009
Saturday, January 24, 2009
Q. How can I Recover a bad superblock from a corrupted ext3 partition to get back my data?
Q. How can I Recover a bad superblock from a corrupted ext3 partition to get back my data? I'm getting following error:
/dev/sda2: Input/output error
mount: /dev/sda2: can't read superblock
How do I fix this error?
A. Linux ext2/3 filesystem stores superblock at different backup location so it is possible to get back data from corrupted partition.
WARNING! Make sure file system is UNMOUNTED.
If your system will give you a terminal type the following command, else boot Linux system from rescue disk (boot from 1st CD/DVD. At boot: prompt type command linux rescue).
Mount partition using alternate superblock
Find out superblock location for /dev/sda2:
# dumpe2fs /dev/sda2 | grep superblock
Sample output:
Primary superblock at 0, Group descriptors at 1-6
Backup superblock at 32768, Group descriptors at 32769-32774
Backup superblock at 98304, Group descriptors at 98305-98310
Backup superblock at 163840, Group descriptors at 163841-163846
Backup superblock at 229376, Group descriptors at 229377-229382
Backup superblock at 294912, Group descriptors at 294913-294918
Backup superblock at 819200, Group descriptors at 819201-819206
Backup superblock at 884736, Group descriptors at 884737-884742
Backup superblock at 1605632, Group descriptors at 1605633-1605638
Backup superblock at 2654208, Group descriptors at 2654209-2654214
Backup superblock at 4096000, Group descriptors at 4096001-4096006
Backup superblock at 7962624, Group descriptors at 7962625-7962630
Backup superblock at 11239424, Group descriptors at 11239425-11239430
Backup superblock at 20480000, Group descriptors at 20480001-20480006
Backup superblock at 23887872, Group descriptors at 23887873-23887878
Now check and repair a Linux file system using alternate superblock # 32768:
# fsck -b 32768 /dev/sda2
Sample output:
fsck 1.40.2 (12-Jul-2007)
e2fsck 1.40.2 (12-Jul-2007)
/dev/sda2 was not cleanly unmounted, check forced.
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Free blocks count wrong for group #241 (32254, counted=32253).
Fix? yes
Free blocks count wrong for group #362 (32254, counted=32248).
Fix? yes
Free blocks count wrong for group #368 (32254, counted=27774).
Fix? yes
..........
/dev/sda2: ***** FILE SYSTEM WAS MODIFIED *****
/dev/sda2: 59586/30539776 files (0.6% non-contiguous), 3604682/61059048 blocks
Now try to mount file system using mount command:
# mount /dev/sda2 /mnt
You can also use superblock stored at 32768 to mount partition, enter:
# mount sb={alternative-superblock} /dev/device /mnt
# mount sb=32768 /dev/sda2 /mnt
Try to browse and access file system:
# cd /mnt
# mkdir test
# ls -l
# cp file /path/to/safe/location
You should always keep backup of all important data including configuration files.
http://www.softpanorama.org/Internals/Filesystems/linux_ext2_ext3.shtml
/dev/sda2: Input/output error
mount: /dev/sda2: can't read superblock
How do I fix this error?
A. Linux ext2/3 filesystem stores superblock at different backup location so it is possible to get back data from corrupted partition.
WARNING! Make sure file system is UNMOUNTED.
If your system will give you a terminal type the following command, else boot Linux system from rescue disk (boot from 1st CD/DVD. At boot: prompt type command linux rescue).
Mount partition using alternate superblock
Find out superblock location for /dev/sda2:
# dumpe2fs /dev/sda2 | grep superblock
Sample output:
Primary superblock at 0, Group descriptors at 1-6
Backup superblock at 32768, Group descriptors at 32769-32774
Backup superblock at 98304, Group descriptors at 98305-98310
Backup superblock at 163840, Group descriptors at 163841-163846
Backup superblock at 229376, Group descriptors at 229377-229382
Backup superblock at 294912, Group descriptors at 294913-294918
Backup superblock at 819200, Group descriptors at 819201-819206
Backup superblock at 884736, Group descriptors at 884737-884742
Backup superblock at 1605632, Group descriptors at 1605633-1605638
Backup superblock at 2654208, Group descriptors at 2654209-2654214
Backup superblock at 4096000, Group descriptors at 4096001-4096006
Backup superblock at 7962624, Group descriptors at 7962625-7962630
Backup superblock at 11239424, Group descriptors at 11239425-11239430
Backup superblock at 20480000, Group descriptors at 20480001-20480006
Backup superblock at 23887872, Group descriptors at 23887873-23887878
Now check and repair a Linux file system using alternate superblock # 32768:
# fsck -b 32768 /dev/sda2
Sample output:
fsck 1.40.2 (12-Jul-2007)
e2fsck 1.40.2 (12-Jul-2007)
/dev/sda2 was not cleanly unmounted, check forced.
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Free blocks count wrong for group #241 (32254, counted=32253).
Fix? yes
Free blocks count wrong for group #362 (32254, counted=32248).
Fix? yes
Free blocks count wrong for group #368 (32254, counted=27774).
Fix? yes
..........
/dev/sda2: ***** FILE SYSTEM WAS MODIFIED *****
/dev/sda2: 59586/30539776 files (0.6% non-contiguous), 3604682/61059048 blocks
Now try to mount file system using mount command:
# mount /dev/sda2 /mnt
You can also use superblock stored at 32768 to mount partition, enter:
# mount sb={alternative-superblock} /dev/device /mnt
# mount sb=32768 /dev/sda2 /mnt
Try to browse and access file system:
# cd /mnt
# mkdir test
# ls -l
# cp file /path/to/safe/location
You should always keep backup of all important data including configuration files.
http://www.softpanorama.org/Internals/Filesystems/linux_ext2_ext3.shtml
fingerprint reader in debian+IBM integrated fingerprint reader
http://linux.spiney.org/debian_gnu_linux_on_an_ibm_thinkpad_t43p_fingerprint_reader
http://www.thinkwiki.org/wiki/How_to_enable_the_fingerprint_reader
http://www.thinkwiki.org/wiki/How_to_enable_the_fingerprint_reader
Friday, January 23, 2009
kernel compilation for supporting more than 1 GB RAM size
Memory Size
This is the main reason you should know how to compile a kernel. Some default kernels will only allow up to 4GB of RAM. Currently I've only noticed this with Fedora Core, Debian and non-servercd CentOS distros. So be sure to browse to the following section:
Processor type and features --->
(And look for...)
High Memory Support (4GB) --->
Change this to 64MB to allow for 4GB and higher RAM.
This is the main reason you should know how to compile a kernel. Some default kernels will only allow up to 4GB of RAM. Currently I've only noticed this with Fedora Core, Debian and non-servercd CentOS distros. So be sure to browse to the following section:
Processor type and features --->
(And look for...)
High Memory Support (4GB) --->
Change this to 64MB to allow for 4GB and higher RAM.
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