MyComputingArt

How to mount an image file and access image content

To get access to the content of a virtual machine image or a ISO file, follow these steps:

associate the file with a loop device node:
# losetup /dev/loop0 /var/otheros.img

list the partition table of the device:

# fdisk -l /dev/loop0 
Disk /dev/loop0: 21.4 GB, 21474837504 bytes 
255 heads, 63 sectors/track, 2610 cylinders 
Units = cylinders of 16065 * 512 = 8225280 bytes 
      Device Boot      Start         End      Blocks   Id  System 
/dev/loop0p1   *           1        2609    20956761    7  HPFS/NTFS

create device map (kpartx is part of multipath-tools package on Ubuntu):

# kpartx -a /dev/loop0
# ls -l /dev/mapper/ 
total 0 
crw-rw---- 1 root root  10, 62 Jul  6  2008 control
brw-rw---- 1 root disk 253,  0 Jul  5 23:18 loop0p1

mount the device partition:
# mount /dev/mapper/loop0p1 /mnt

Posted by: Z24 | Thu, Jul 10 2008 | Category: /linux | Permanent link | home
Tagged as: command-line, linux, shell

Running Windows XP in Xen from its own partition

Some months ago I made some experiments with Xen and I succeeded to install and run Windows XP as a guest using Xen 3.0. In that case Windows was located in a single file and was installed through Xen. My purpose now is to make Xen running an already installed Windows from its own partition. Just to be more specific, this is my machine configuration:

Ubuntu Dapper Drake 6.06 is located on a SATA disk, set as first boot disk
Windows XP is located on a EIDE disk, set as second boot disk
Dual boot is made by grub

I want to log into linux and run my existing Windows XP from its own partition on the EIDE disk.

See full post ...

Posted by: Z24 | Mon, Dec 03 2007 | Category: /linux | Permanent link | home
Tagged as: grub, linux, ubuntu, virtualization, windows, xen, xp

Ubuntu Dapper Drake 6.06 amd64 and Windows XP in Xen 3.0

I am coming from a bloody week of wrestling against packages, bugs and "make world"s trying to run Xen in Ubuntu 6.06 amd64 on an AM2 3800+ and to make a Windows XP Pro domU.
I searched on the web some resources that would explain how to run Windows on Xen and I found some very good tutorial that unfortunately don't fit exactly my configuration and my purpose. These are the sites I took as a basis for my setup:

These are all the steps I did and the problems I encountered during this Calvary :-) (I come from Windows with a little linux/unix background):

See full post ...

Posted by: Z24 | Mon, Nov 26 2007 | Category: /linux | Permanent link | home
Tagged as: linux, ubuntu, virtualization, windows, xen, xp

Recover "Logical sector size is 0" with dd

A few hours ago while I was using my pc suddenly Windows froze completely (mouse was stuck and Ctrl+Alt+Del did nothing). It's not astonishing but I was quite surprised because such a freeze never happened since I began using Windows XP on my new pc.
The problem appeared at the reboot: grub, the bootloader on /dev/sda, showed this error message:

13 : Invalid or unsupported executable format

I have a dual boot configuration with Windows XP booting from a EIDE disk and Ubuntu booting from a SATA disk, so I entered Ubuntu, successfully; /dev/hda1 (the Windows partition) was not mounted while /dev/hda5 and /dev/hda6 were; attempting to mount it resulted in

Special device /dev/hda1 does not exist

At reboot I started Windows XP Recovery Console from the Windows CD and tried CHKDSK.EXE, and this was the outcome:

The volume appears to contain one or more unrecoverable problems

I booted again linux to launch fsck and see it fail:

Logical sector size is zero.

Then I found the solution in ubuntu forum:

root@am2:/home/z24# dd if=/dev/hda1 of=/defmedia/bkup_fat32_hda1.img bs=512 count=2048000 conv=noerror,sync
2048000+0 records in
2048000+0 records out
1048576000 bytes (1.0 GB) copied, 43.61 seconds, 24.0 MB/s

root@am2:/home/z24# dd if=/defmedia/bkup_fat32_hda1.img of=/home/z24/sector6.bin bs=512 count=1 skip=6 conv=noerror,sync
1+0 records in
1+0 records out
512 bytes (512 B) copied, 0.011544 seconds, 44.4 kB/s

root@am2:/home/z24# dd if=/home/z24/sector6.bin of=/dev/hda1 bs=512 count=1 conv=noerror,sync,notrunc
1+0 records in
1+0 records out
512 bytes (512 B) copied, 0.030644 seconds, 16.7 kB/s

Explanation:

the first dd makes a backup of the first gigabyte of the Windows partition: I copied 1 GB only because I didn't have enough space on a ext2fs to backup all the 28 GB of /dev/hda1.
the second dd extracts the sixth sector to a temporary file: as reported by Microsoft KB247575, "The backup FAT32 boot sector is located at sector 6 of the logical drive".
the third dd copies the extracted sector 6 to sector 0 of /dev/hda1.

In the original post the partition that was just backupped with dd was also checked with losetup and mount. Thanks a lot to the ubuntuforums user Onlymee for his post!

Update 13.09.2008

The same problem happened again today and gave me the opportunity to complete the series of error messages :)
The first, at boot time, was the same:

grub: 13 : Invalid or unsupported executable format

Mounting the partition (mount -t vfat /dev/sda1 /mnt):

mount: wrong fs type, bad option, bad superblock on /dev/sda1, missing codepage or other error

dmesg | grep sda1

VFS: Can't find a valid FAT filesystem on dev sda1

But fdisk -l /dev/sda shows the partition table.
fsck.vfat /dev/sda1 (executed from Ubuntu 8.04 alternate cd)

Cluster size is zero

The solution was exactly the same: copy the sixth sector back to the first. And voilà, it booted.

Posted by: z24 | Sun, Jun 24 2007 | Category: /hardware | Permanent link | home
Tagged as: error, grub, hardware, linux, system recover

Debian on Windows with VMWare, Linux applications in Windows using X server

With this little and very simple tutorial I will explain what I did to:

install VMWare for Windows
run Debian virtual appliance
connect from Windows host to Linux guest and connect from Linux guest to Windows host
run seamless Linux applications in the Windows graphical environment using an X server

See full post ...

Posted by: Z24 | Mon, Oct 09 2006 | Category: /windows | Permanent link | home
Tagged as: client-server, linux, security, virtualization, VMWare, windows

Ubuntu 6.06 Dapper Drake 32 bit on Windows XP with Qemu, Qemu networking, Linux applications in Windows using X server

With this little tutorial I will explain what I did to:

install Qemu and its accelerator kqemu
create an image file where the guest operating system will be installed
install and then run Ubuntu 6.06 Dapper Drake 32 bit as a guest operating system
connect from Windows host to Linux guest with qemu redir option
connect from Windows host to Linux guest and connect from Linux guest to Windows host using tap driver
run seamless Linux applications in the Windows graphical environment using an X server

See full post ...

Posted by: Z24 | Sat, Sep 16 2006 | Category: /windows | Permanent link | home
Tagged as: client-server, linux, qemu, virtualization, windows, xp

Install and boot Windows on a second hard disk

I have a SATA disk and a EIDE disk, I installed Linux on the SATA disk and now I want to install Windows on the EIDE disk.
Because Windows must be installed on the disk that boot first, I entered BIOS and changed the boot order as this:
cdrom
EIDE disk
SATA disk
Then I installed Windows on the EIDE disk.
I want to configure dual boot this way:

default choice: Linux (booting from SATA disk)
second choice: Windows (booting from EIDE disk)

I changed BIOS boot order as it was previously (SATA disk before EIDE disk) and booted Linux, then I added these lines to /boot/grub/menu.list (on Ubuntu or Debian; if grub is not installed try apt-get install grub):

title WinXP
map (hd0,0) (hd1,0)
map (hd1,0) (hd0,0)
rootnoverify (hd1,0)
chainloader +1

That means Windows believes the EIDE disk is the first and SATA is the second, so it's happy and if I reboot and choose WinXP from grub menu it starts.

Posted by: Z24 | Wed, Aug 30 2006 | Category: /windows | Permanent link | home
Tagged as: grub, linux, windows

Execute a command at shutdown

To dismount TrueCrypt volumes at shutdown and reboot time, I created a script, put it in/etc/init.d/ and symlinked it into the needed /etc/rc?.d/ directories using update-rc.d.
Here is the detail:

See full post ...

Posted by: Z24 | Sun, Aug 27 2006 | Category: /linux | Permanent link | home
Tagged as: command-line, linux, programming, script, shell

Pausing a command

How to pause / suspend / sleep a running command in a terminal?
Press Ctrl+S
How to resume the paused command?
Press Ctrl+Q

Posted by: Z24 | Sun, Aug 27 2006 | Category: /linux | Permanent link | home
Tagged as: command-line, linux, shell

How to rename multiple files from bash

Rename all *html files to *test:

for x in `ls *html`; do mv $x `echo $x | sed -e "s/html/test/"`; done

Bash for:

for var in some-list ; do command ; done

Posted by: Z24 | Sun, Aug 27 2006 | Category: /linux | Permanent link | home
Tagged as: command-line, linux, programming, script, shell

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