Monday, 24 December 2012

Keeping a LiveCD distribution up-to-date

After learning how to put a number of LiveCD distributions in a USB stick (all with persistent modes):, I have quickly started using that quite a lot, and it has soon become clear that after a while I need to keep the distributions up-to-date. So, I learnt how to keep the distribution relevant and up-to-date and the persistent file small enough. I mostly followed, but I modified slightly:

angelv@palas:~$ mkdir /tmp/iso /tmp/squash
angelv@palas:~$ sudo mount -o loop /media/angelv/angelv/ubuntustudio-12.10-dvd-amd64.iso /tmp/iso
[sudo] password for angelv: 
mount: warning: /tmp/iso seems to be mounted read-only.
angelv@palas:~$ sudo mount -o loop /tmp/iso/casper/filesystem.squashfs /tmp/squash

angelv@palas:~$ mkdir /tmp/changes
angelv@palas:~$ sudo mount /media/angelv/angelv/persistent/ubuntustudio/casper-rw /tmp/changes

angelv@palas:~$ mkdir /tmp/merged
angelv@palas:~$ sudo mount -t aufs -o br=/tmp/changes=rw:/tmp/squash none /tmp/merged

angelv@palas:~$ sudo mksquashfs /tmp/merged/ ~/ubuntustudio.squashfs
angelv@palas:~$ sudo umount /tmp/merged /tmp/squash /tmp/changes 

angelv@palas:~$ mkdir -p ubuntu_studio_changed/casper
angelv@palas:~$ mv  ubuntustudio.squashfs ubuntu_studio_changed/casper/filesystem.squashfs
angelv@palas:~$ mkdir /tmp/newiso
angelv@palas:~$ sudo mount -t aufs -o br=ubuntu_studio_changed=rw:/tmp/iso none /tmp/newiso

angelv@palas:~$ cd /tmp/newiso/
angelv@palas:/tmp/newiso$ sudo genisoimage -R -b isolinux/isolinux.bin -no-emul-boot -boot-load-size 4 -boot-info-table -o /home/angelv/new_ubuntu_studio.iso /tmp/newiso/

angelv@palas:/tmp/newiso$ cd
angelv@palas:~$ sudo umount /tmp/newiso 
angelv@palas:~$ sudo umount /tmp/iso 

angelv@palas:~$ mv new_ubuntu_studio.iso /media/angelv/angelv/ubuntustudio-12.10-dvd-amd64.iso
angelv@palas:~$ dd if=/dev/zero of=casper-rw bs=1M count=3072
angelv@palas:~$ mkfs.ext3 -F casper-rw
angelv@palas:~$ mv casper-rw /media/angelv/angelv/persistent/ubuntustudio/casper-rw

I try it, and I can see that I get the same as I had before, but now the casper-rw file is empty, so I can start a new round of customizations. Installation / removal of software goes all to the casper-rw file, so when we recreate the ISO file to incorporate the casper-rw file, we are also generating a ISO file with all the same software as our persistent-mode version.

Saturday, 8 December 2012

Remote Desktop with x11vnc

For years now I have been using screen (byobu) for remote connection to my workstation. I do most of my work in the terminal window, so that works well, but for those moments when I needed to also work graphically I have been slowly migrating...

Years ago I was using VNC, but at the time the whole thing was quite slow and a bit frustrating for regular use. A couple of years ago I discovered Xpra, with the up-to-date fork Winswitch. Very nice project: it works like screen but for X11, so I could keep graphical applications open and don't worry about broken internet connections. Also, I didn't have to export the whole desktop, only the applications that I was interested in. The downside was this would generate another X11 session, so that if at work I was doing some exciting work in an application and later I wanted to continue that from home it was not possible. I had to restart the application (not too bad, but a bit cumbersome at times).

In any case I was happy with xpra until I switched to Ubuntu 12.10. For some reason (probably due to the Nvidia drivers I'm using at my workstation) I could not get it working (it was working OK with the same hardware and Ubuntu 11.10, so perhaps I just had to spend some more time configuring it), so I gave up and tried x11vnc. x11vnc will export the whole desktop (I would prefer just individual applications), but not a new one, just your "real X11 display (i.e. one attached to a physical monitor, keyboard, and mouse: a Workstation or a SunRay session) from far away".  This has the advantage that I don't have to plan in advance when I'm going to work remotely or end up (as it was happening often to me before) with the same application open twice (one in my real X11 display and another one in the virtual one created by xpra). I was expecting, as for my old VNC experience, sluggish behaviour again over my home ADSL connection, but I was pleasantly surprised.

Installation was very easy. At the workstation apt-get install x11vnc, and at the laptop apt-get install  ssvnc

Running it is also very easy. After reading the manual page, I first generated a vnc password with the command vncpasswd, and then I came up with the following command line to run at the workstation:

x11vnc -display :0 -rfbauth .vnc/passwd -localhost -rfbport 5900 -forever -ncache -bg -o .vnc/x11vnc.log

The arguments mean in turn: it will attach to the "real X11 display" (-display :0) in my workstation;  it will use the previously generated .vnc/passwd file for authentication; for extra security it will allow only connections from localhost (obviouly I didn't get this working to connect physically from my workstation at work, but from my home laptop I create a ssh tunnel to the port 5900, so that when I connect to x11vnc via the viewer, the connection looks like it came from localhost); it will use port 5900; the server will not quite after the viewer exits, so this will be available forever; it will send extra information to the viewer, so it can cache portions of the display to make it work faster; -bg will send it to the background, and a log will be generated at .vnc/x11vnc.log.

Connecting remotely to my workstation is then performed via ssvnc. I just connect to localhost (will use by default port 5900, which is being tunnelled to my workstation):

Also, the -ncache option sends a lot of extra data that I don't want to see, so you can do that by cropping the display in the Y direction (in my case to 1024 pixels, which matches the resolution at my workstation):

With that in place, the experience is pretty good. Don't take my word for it and see a recording of it in action:

EDIT (13/12/2012): In order to avoid other people interacting with my workstation when I'm connected remotely I came up with the following solution, which works pretty well. This is not bulletproof, and a malicious user could easily jump these protections, but to avoid accidental use of my workstation while I'm working remotely is sufficient. I now run x11vnc as:

x11vnc -display :0 -rfbauth .vnc/passwd -accept "/home/angelv/.vnc/" -gone "/home/angelv/.vnc/" -localhost -rfbport 5900 -ncache -forever -o .vnc/x11vnc.log

The only difference is the -accept argument, which points to (this will: physically turn off the monitors, and they will not come back to life by moving the mouse or typing at the keyboard; disable the mouse and the keyboard, so somebody cannot interact with my session even accidentally):

sudo vbetool dpms off
xinput set-prop "Dell Dell USB Keyboard" "Device Enabled" 0
xinput set-prop "Dell Premium USB Optical Mouse" "Device Enabled" 0

and the -gone argument, which points to (which will revert the stuff done by

sudo vbetool dpms on
xinput set-prop "Dell Dell USB Keyboard" "Device Enabled" 1
xinput set-prop "Dell Premium USB Optical Mouse" "Device Enabled" 1

vbetool needs to be run with administrator privileges, but I include myself in the sudoers list (with visudo), so that I don't need to type the password for it:

angelv ALL=NOPASSWD:/usr/sbin/vbetool

Tuesday, 27 November 2012

Multi-boot USB Stick

Some time ago I discovered MultiSystem, which easily let's you create a USB stick with a number of different distributions (some basic instructions, for example, at

The program is quite nice as it is (though the GUI is a little bit awkward), but I wanted to have a couple of things done differently, so the resulting USB stick could be more suited to my needs. Mainly two things:

  1. Allow persistent mode for several of the distros (by default you can only get persistent mode for one of them).
  2. Allow the usage of some of the space of the pendrive as a common storage area for all distributions.

In order to get it done I first installed MultiSystem:

sudo sh -c 'echo "deb all main" >> /etc/apt/sources.list'
wget -q -O- | sudo apt-key add -
sudo apt-get update
sudo apt-get install multisystem

Then, using the MultiSystem GUI I installed Xubuntu 12.10 and Linux Mint 14 in the pendrive. Then I chose one of them and using MultiSystem added the persistent mode. This will create the appropriate entry in the grug.cfg file in the pendrive, and it will also create a file, casper-rw. I delete the created casper-rw file and created my own one as ext3 (the one created with MultiSystem is ext2), instructions from

dd if=/dev/zero of=casper-rw bs=1M count=1024
mkfs.ext3 -F casper-rw
Copy the new casper-rw file to the pendrive

But instead of leaving the casper-rw file in the root directory of the pendrive, I put it in the directory:


After that I modified the grub.cfg in the pendrive (/boot/grub/grub.cfg) so that it will look for that particular casper-rw file, and a different username and hostname will be used (the relevant options are persistent-path, hostname, username and userfullname, instructions taken from

linux (loop)/casper/vmlinuz root=UUID=4088-F6F9 debian-installer/language=en keyboard-configuration/layoutcode=es  iso-scan/filename=/xubuntu-12.10-desktop-amd64.iso boot=casper showmounts persistent persistent-path=/persistent/xubuntu/ hostname=nomada username=angelv userfullname=AngeldeVicente file=/cdrom/preseed/xubuntu.seed noprompt quiet splash --

With that we have the way open to repeat the procedure for Linux Mint, another casper-rw will be created, which we get rid of and follow the steps above to create a personalized casper-rw file for that particular distro.

When booting a computer from the resulting USB stick, the GRUB options window looks like the following (there are two options for Xubuntu and two for Linux Mint: one of them will ignore the persistent (casper-rw) file and will just boot the clean liveCD version; the second one will use the persistent file, so that we can install some new software, change some settings, etc. and they will survive reboots):

As for the common storage for all the distributions, that was simply done with gparted, so that I resized the fat32 partition to leave space (10GB) for another partition (ext3), which can be mounted from the live USB distros, and used as a common space for documents, etc.

As an example, here it is the Linux Mint (with persistent option) desktop, in which the "common" partition is the ext3 partition created in the USB stick itself for common storage across the different distros: 

This is not an issue for me yet, but at some point I will probably make a lot of changes to the different distros. In order to merge the changes with the original LiveCD distribution, I will try to follow the instructions at

EDIT (21/12/2012): After a few successful installations, I found that one of the persistence files was getting small, so I looked for information on resizing the casper-rw file. For adding to the file, this works OK:

dd if=/dev/zero bs=1M count=500 >> casper-rw
resize2fs casper-rw

For decreasing the size of the casper-rw, we probably should go something like:

dd if=/dev/zero of=newfile bs=1M count=number of blocks
mkfs.ext3 -F

mount -o loop oldfile /mnt/mountold
mount -o loop newfile /mnt/mountnew

Sunday, 18 November 2012

Lexmark X1190 with Ubuntu 12.10 (64 bits)

I have upgraded to Ubuntu 12.10, and the steps to make the X1190 work with this version are very similar to what we did for Ubuntu 11.10 (, but easier.

The scanner works by default, so nothing to be done in there.

For the printer, the steps are the same as per 11.10, but we don't need to install libstdc++5:i386, since that is now part of ia32-libs.

Friday, 13 July 2012

Lexmark X1190 with Ubuntu 11.10 (64 bits)

I have installed this printer for a number of Ubuntu distributions, and I always forget to write the details, so here they go:

Printer (mostly from
  1. With synaptic, install ia32-libs, libstdc++5:i386 and rpm
  2. Download  CJLZ600LE-CUPS-1.0-1.TAR.gz, for example from:
  3. tar xzvf CJLZ600LE-CUPS-1.0-1.TAR.gz
  4. tail -n +143 > install.tar.gz
  5. tar xzvf install.tar.gz
  6. sudo rpm --force-debian -ivh z600cups-1.0-1.i386.rpm z600llpddk-2.0-1.i386.rpm --nodeps
  7. sudo service cups restart
  8. configure printer from the system settings with driver Lexmark-Z600


  1. I get rid of libsane and libsane-extras
  2. I follow more or less the instructions by Ashley Hooper at:
  3. Instead of the 386 packages, I install the amd64 ones: and
  4. In order to avoid upgrading these by mistake, I fix them:
    gksudo gedit /etc/apt/preferences.d/libsane
    Now paste the below contents into the file, save and exit.
    Package: libsane
    Pin: version 1.0.21-9
    Pin-Priority: 900
  5. I confirm it is working using the apt-cache policy command: $ apt-cache policy libsane
  6. Now either simple-scan or xsane work nicely with the scanner.