Using Rsync

Some quick rsync examples

rsync -av /memstick/ /mymaindisk/
This will rsync the memstick directory to mymaindisk directory preserving all aspects of the files with the archive switch and the verbose switch will show whats happening.

rsync -avz /memdisk/ me@myserver:/backupdir/
This will do rsync over ssh rather than scp, using -a archive switch -z switch this signifies use compression over the link.

Ubuntu Server Screen Blank

Problem when rebooting Ubuntu 11.04 Server X86 after fresh install.
It caused the screen to be blank and a monitor message of overrange settings. This was traced to the setting of gfxmode=auto in the /boot/grub/grub.cfg file.

Note: you have to boot Ubuntu into rescue mode using the media CD/DVD/Memory Stick you used to install the system with.
From the command prompt make the /boot/grub/grub.cfg writable using chmod +w /boot/grub/grub.cfg command.
Now edit the file using vim /boot/grub/grub.cfg command.

The settings that worked for me were as follows gfxmode=1024x768 and with an entry gfxplayload=keep added directly after the gfxmode line.
After editing hit esc key then type wq and then hit enter this will write the file and quit vim.

Now reboot your system and hope it works.

What a mucking around to fix this stupid fault.

Information Source I used

Add sudo to CentOS

Install the sudo package
# yum install sudo


Edit the sudo file by removing the # from the # %wheel ALL=(ALL) ALL to uncomment it.
# visudo

Save the changes and quit.
:wq


gpasswd -a username wheel

Change to sudo su.
sudo su -

Confirm that you can login with your username, then disable the root login.
passwd -l root

TP-Link MR3220 Debricking

I bricked my MR3220 router with an OpenWRT firmware upload. I did manage to get it back by soldering a 4 pin header on its pcb to allow connection to its serial port. I used a Sparkfun FTDI Basic Breakout - 3.3V USB to serial port converter . I used minicom in Ubuntu 11.04 to communicate with the MR3220.

Photo showing the FTDI Basic Breakout - 3.3V USB to serial port converter.
MR3220 Debricking Procedure
Do this:
- Power off the router
- Connect the serial cable to the router and the computer
- Connect the Ethernet cable to the router and the computer
- Set the IP address of the NIC in your computer fixed at 192.168.1.27
- Start the tftpd server I used tftpgui and placed the firmware from the TP-Link website renamed to code.bin in the root directory of the tftp server as defined in its settings.
I used info obtained from OpenWRT Wiki and the procedure I used is below
- Start minicom with parameters 8 bit, no parity, one stop bit, 115200 baud, no flow control and no xon-xoff.
- Power the router on
- Boot messages will appear on the minicom terminal
- When the message "autoboot in 1 second .." appears quickly enter password tpl you will have to type quickly. This should interrupt the boot process and you should see the prompt:
ar7100>

To program the new image:
Erase the memory
ar7100> erase 0x9f020000 +0x3c0000
Load the new firmware
ar7100> tftpboot 0x81000000 code.bin
Copy memory bytes into flash memory
ar7100> cp.b 0x81000000 0x9f020000 0x3c0000
Boot kernel image from flash memory location
ar7100> bootm 0x9f020000

To transfer image via Kermit (Serial Port)
You set the router up to receive the file via Minicom using the following commands. Erase the memory
ar7100> erase 0x9f020000 +0x3c0000
Now load the binary file
loadb 0x81000000
Exit Minicom Ctrl A Z X Fire up Kermit:-
set line /dev/ttyUSB0
set speed 115200
set carrier-watch off
set handshake none
set flow-control none
robust
set file type bin
set file name lit
set rec pack 1000
set send pack 1000
set window 5
send openwrt-ar71xx-generic-tl-mr3220-v1-squashfs-factory.bin
Back to minicom:-
Copy memory bytes into flash memory
ar7100> cp.b 0x81000000 0x9f020000 0x3c0000
Boot kernel image from flash memory location
ar7100> bootm 0x9f020000

Photo of MR3220 showing the four pin header location and pin outs.

That's hopefully it and router should now work.
The router admin webpage is now on 192.168.1.254 , Note: I found that the password was still set to the password I had set when I first got the router and not the manufacturers default password as I expected with a reflash.

Create a Video Using DeVeDe

DeVeDe is a CD/DVD creator package for Linux. In Ubuntu sudo apt-get install devede, this will install the package.
Run the program in Gnome by selecting Applications -> Sound & Video -> DeVeDe CD/DVD Creator.
In the program I chose Video DVD. Changed the title by right-clicking on Title. Add the video vob file from the mini DVD source. In the advanced options I chose "FMMpeg deinterlacing filter" as I found that using the default "Don't deinterlace" gave horrible comb effects when the video was playing. The final file created by DeVeDe is an iso file that can be burned on a DVD using K3b.

VirtualBox

Create a VM
VBoxManage –help


VBoxManage createvm --name "MyvmServer" --register
VBoxManage modifyvm "MyvmServer" --memory 256 --acpi on --boot1 dvd --nic1 bridged --bridgeadapter1 eth0
VBoxManage createhd --filename MyvmServer.vdi --size 10000 --register
VBoxManage storagectl "MyvmServer" --name "IDE Controller" --add ide
VBoxManage storageattach "MyvmServer" --storagectl "IDE Controller" --port 0 --device 0 --type hdd --medium MyvmServer.vdi
VBoxManage storageattach "MyvmServer" --storagectl "IDE Controller" --port 1 --device 0 --type dvddrive --medium /home/MyvmServer.iso


Start a VM with VboxHeadless
VBoxHeadless --startvm "MyvmServer"
VBoxManage controlvm "MyvmServer" poweroff
VBoxManage controlvm "MyvmServer" pause
VBoxManage controlvm "MyvmServer" reset
VBoxHeadless –help

Import an existing VM
VM with the name myvm that needs to be reused. A directory contains myvm in the VirtualBox directory. The myvm directory will contain the myvm.xml file. Copy the myvm directory (including the myvm.xml file) to the new Machines directory.
In addition copy the myvm.vdi file from the old VDI directory to the new one.
Register the imported VM:
VBoxManage registervm somedirectory/myvm/myvm.xml

Reference Page
The above link contains more info on VM's.

Remove CentOS Xen

Install Standard Kernel
yum install kernel

Remove Xen Kernel
yum remove xen kernel-xen

Edit Grub to Select Correct Kernel
/boot/grub/grub.conf