Debian | Technology Tales

Compressing a VirtualBox VDI file for a Linux guest

6^th June 2016

In a previous posting, I talked about compressing a virtual hard disk for a Windows guest system running in VirtualBox on a Linux system. Since then, I have needed to do the same for a Linux guest following some housekeeping. Because the Linux distribution used is Debian, the instructions are relevant to that and maybe its derivatives such as Ubuntu, Linux Mint and their like.

While there are other alternatives like dd, I am going to stick with a utility named zerofree to overwrite the newly freed up disk space with zeroes to aid compression later on in the process for this and the first step is to install it using the following command:

apt-get install zerofree

Once that has been completed, the next step is to unmount the relevant disk partition. Luckily for me, what I needed to compress was an area that I reserved for synchronisation with Dropbox. If it was the root area where the operating system files are kept, a live distro would be needed instead. In any event, the required command takes the following form, with the mount point being whatever it is on your system (/home, for instance):

sudo umount [mount point]

With the disk partition unmounted, zerofree can be run by issuing a command that looks like this:

zerofree -v /dev/sdxN

Above, the -v switch tells zerofree to display its progress and a continually updating percentage count tells you how it is going. The /dev/sdxN piece is generic with the x corresponding to the letter assigned to the disk on which the partition resides (a, b, c or whatever) and the N is the partition number (1, 2, 3 or whatever; before GPT, the maximum was 4). Putting all this together, we get an example like /dev/sdb2.

Once, that had completed, the next step is to shut down the VM and execute a command like the following on the host Linux system ([file location/file name] needs to be replaced with whatever applies on your system):

VBoxManage modifyhd [file location/file name].vdi --compact

With the zero filling in place, there was a lot of space released when I tried this. While it would be nice for dynamic virtual disks to reduce in size automatically, I accept that there may be data integrity risks with those, so the manual process will suffice for now. It has not been needed that often anyway.

Installing FreeBSD in a VirtualBox Virtual Machine

2^nd March 2014

With UNIX being the basis of Linux, I have a soft spot for trying out any UNIX that can be installed on a PC. For a while, I had OpenSolaris on the go and even vaguely recall having a look at one of the BSD's. However, any recent attempt to install one of the latter, and there are quite a few around now, got stymied by some sort of kernel panic caused by using AMD CPU's. With the return to the Intel fold arising from the upgrade of my main home PC last year, it perhaps was time to try again.

The recent release of FreeBSD 10.0 was the cue and I downloaded a DVD image for a test installation in a VirtualBox virtual machine with 4 GB of memory and a 32 GB virtual hard drive attached (expanding storage was chosen so not all the allocated space has been taken so far). The variant of FreeBSD chosen was the 64-bit x86 one, and I set to installing it in there. Though not as pretty in appearance as those in various Linux distros, the installer was not that user unfriendly to me. Mind you, I have experience of installing Arch Linux, which might have acclimatised me somewhat.

Those installation screens ask about the keyboard mapping that you want, and I successfully chose one of the UK options. There was limited opportunity for adding extras, though there was a short list of a few from which I made some selections. Given that user account set up also was on offer, I would have been better off knowing what groups to assign for my personal user account to have to avoid needing to log in as root so often following system start up later. Otherwise, all the default options were sufficient.

When the installation process was complete, it was time to boot into the new system and all that was on offer was a command line log in session. After logging in as root, it was time to press pkg into service to get a desktop environment in place. The first step was to install X:

pkg install xorg

Then, it was time to install a desktop environment. While using XFCE or KDE were alternatives, I chose GNOME 2 due to familiarity and more extensive instructions on the corresponding FreeBSD handbook page. Issuing the following command added GNOME and all its helper applications:

pkg install gnome2

So that GNOME starts up at the next reboot, some extra steps are needed. The first of these is to add the following line into /etc/fstab:

proc /proc procfs rw 0 0

Then, two lines were needed in /etc/rc.conf:

gdm_enable="YES" gnome_enable="YES"

The first enables the GNOME display manager, while the second activates other GNOME programs that are needed for a desktop session to start. With each of these in place, I got a graphical login screen at the next boot time.

With FreeBSD being a VirtualBox Guest, it was time to consult the relevant FreeBSD manual page. Here, there are sections for a number of virtual machine tools, so a search was needed to find the one for VirtualBox. VirtualBox support for FreeBSD is incomplete in that there is no installation media for BSD systems, while Linux and Solaris are supported along with Windows. Therefore, it is over to the FreeBSD repositories for the required software:

pkg install virtualbox-ose-additions

Aside from the virtual machine session not capturing and releasing the mouse pointer automatically, that did everything that was needed, even if it was the open source edition of the drivers and their proprietary equivalents. To resolve the mouse pointer issue, I needed to temporarily disable the GNOME desktop session in /etc/rc.conf to drop to a console only session where xorg.conf could be generated using the following commands:

Xorg -configure cp xorg.conf.new /etc/xorg.conf

In the new xorg.conf file, the mouse section needs to be as follows:

Section "InputDevice" Identifier "Mouse0" Driver "vboxmouse" EndSection

If it doesn't look like the above, and it wasn't the case for me, then it needs changing. Also, any extra lines from the default set up also need removing, or the mouse will not function as it should. The ALT+F1 (for accessing GNOME menus) and ALT+F2 (for running commands) keyboard shortcuts then become crucial when your mouse is not working as it should and could avert a panic too; knowing that adjusting a single configuration file will resolve a problem when doing so is less accessible is not a good feeling as I discovered to my own cost. The graphics settings were fine by default, but here's what you should have in case it isn't for you:

Section "Device" ### Available Driver options are:- ### Values: <i>: integer, <f>: float, <bool>: "True"/"False", ### <string>: "String", <freq>: "<f> Hz/kHz/MHz" ### [arg]: arg optional Identifier "Card0" Driver "vboxvideo" VendorName "InnoTek Systemberatung GmbH" BoardName "VirtualBox Graphics Adapter" BusID "PCI:0:2:0" EndSection

The next step is to ensure that your HAL settings are as they should. I needed to create a file in /usr/local/etc/hal/fdi/policy called 90-vboxguest.fdi that contains the following:

<?xml version="1.0" encoding="utf-8"?>  <deviceinfo version="0.2"> <device> <match key="info.subsystem" string="pci"> <match key="info.product" string="VirtualBox guest Service"> <append key="info.capabilities" type="strlist">input</append> <append key="info.capabilities" type="strlist">input.mouse</append> <merge key="input.x11_driver" type="string">vboxmouse</merge> <merge key="input.device" type="string">/dev/vboxguest</merge> </match> </match> </device> </deviceinfo>

With all that set, it is time to ensure that the custom user account is added to the wheel and operator groups using this command:

pw user mod [user name] -G wheel operator

Executing the above as root means that the custom account can run the su command so that logging in as root at the start of a desktop session no longer is needed. That is what being in the wheel group allows, so anyone in the operator group can shut down or restart the system. Since both are facilities readily available on Linux, so I fancied having them in FreeBSD too.

Being able to switch to root in a terminal session meant that I could go on to add software like Firefox, LibreOffice, GIMP, EMACS, Geany, NetBeans, Banshee and so on. Though there may be a line of opinion that FreeBSD is a server operating system, all of these make it more than passable for serving as a desktop one too. There may be no package management GUI as such and the ones that come with GNOME do not work either, yet anyone familiar with command line working will get around that.

While FreeBSD may be conservative, that has its place too, and being able to build up a system one item at a time teaches far more than getting everything already sorted in one hit. So far, there is enough documentation to get me going, leaving me to see where else things go too. So far, the OS hasn't been that intimidating, which is good to see.

Installing Citrix Receiver 13.0 in Ubuntu GNOME 13.10 64-bit

28^th November 2013

Installing the latest version of Citrix Receiver (13.0 at the time of writing) on 64-bit Ubuntu should be as simple as downloading the required DEB package and double-clicking on the file so that Ubuntu Software Centre can work its magic. Unfortunately, the 64-bit DEB file is faulty, so that means that the Ubuntu community how-to guide for Citrix still is needed. In fact, any user of Linux Mint or another distro that uses Ubuntu as its base would do well to have a look at that Ubuntu link.

For the sake of completeness, I still am going to let you in on the process that worked for me. Once the DEB file has been downloaded, the first task is to create a temporary folder where the DEB file's contents can be extracted:

mkdir ica_temp

With that in place, it then is time to do the extraction, and it needs two commands with the second of these need to extract the control file while the first extracts everything else.

sudo dpkg-deb -x icaclient- ica_temp sudo dpkg-deb --control icaclient- ica_temp/DEBIAN

It is the control file that has been the cause of all the bother because it refers to unavailable dependencies that it really doesn't need anyway. To open the file for editing, issue the following command:

sudo gedit ica_temp/DEBIAN/control

Then change line 7 (it should begin with Depends:) to: Depends: libc6-i386 (>= 2.7-1), lib32z1, nspluginwrapper. While there are other software packages in there that Ubuntu no longer supports, they are not needed anyway. With the edit made, and the file saved, the next step is to build a new DEB package with the corrected control file:

dpkg -b ica_temp icaclient-modified.deb

Once you have the package, the next step is to install it using the following command:

sudo dpkg -i icaclient-modified.deb

If it fails, then you have missing dependencies and the following command should sort these before a re-run of the above command again:

sudo apt-get install libmotif4:i386 nspluginwrapper lib32z1 libc6-i386

With Citrix Receiver installed, there is one more thing that is needed before you can use it freely. This is to put Thawte security certificate files into /opt/Citrix/ICAClient/keystore/cacerts. What I had not realised until recently was that many of these already are in /usr/share/ca-certificates/mozilla and linking to them with the following command makes them available to Citrix Receiver:

sudo ln -s /usr/share/ca-certificates/mozilla/* /opt/Citrix/ICAClient/keystore/cacerts/

Another approach is to download the Thawte certificates and extract the archive to /tmp/. From there they can be copied to /opt/Citrix/ICAClient/keystore/cacerts and I copied the Thawte Personal Premium certificate as follows:

sudo cp /tmp/Thawte Root Certificates/Thawte Personal Premium CA/Thawte Personal Premium CA.cer /opt/Citrix/ICAClient/keystore/cacerts/

Until I found out about what was in the Mozilla folder, I simply picked out the certificate mentioned in the Citrix error message and copied it over like the above. Of course, all of this may seem like a lot of work to those who are non-tinkerers and I have added a repaired 64-bit DEB package that incorporates all of the above and should not need any further intervention aside from installing it using GDebi, Ubuntu's Software Centre, dpkg or anything else that does what's needed.

A little look at Debian 7.0

12^th May 2013

Having a virtual machine with Debian 6 on there, I was interested to hear that Debian 7.0 is out. In another VM, I decided to give it a go. Installing it on there using the Net Install CD image took a little while but proved fairly standard with my choice of the GUI-based option. GNOME was the desktop environment with which I went and all started up without any real fuss after the installation was complete; it even disconnected the CD image from the VM before rebooting, a common failing in many Linux operating installations that lands into the installation cycle again unless you kill the virtual machine.

Though the GNOME desktop looked familiar, a certain amount of conservatism reigned too, since the version was 3.4.2. That was no bad thing, since raiding the GNOME Extension site for a set of mature extensions was made easier. In fact, a certain number of these were included in the standard installation anyway and the omission of a power off entry on the user menu was corrected as a matter of course without needing any intervention from this user. Adding to what already was there made for a more friendly desktop experience in a short period of time.

Debian's variant of Firefox, IceWeasel, is version 10 so a bit of tweaking is needed to get the latest version. LibreOffice is there now too, and it's version 3.5 rather than 4. Shotwell too is the older 0.12 and not the 0.14 that is found in the likes of Ubuntu 13.04. As it happens, GIMP is about the only software with a current version and that is 2.8; a slower release cycle may be the cause of that, though. All in all, the general sense is that older versions of current software are being included for the sake of stability and that is sensible too, so I am not complaining very much about this at all.

The reason for not complaining is that the very reason for having a virtual machine with Debian 6 on there is to have Zinio and Dropbox available too. Adobe's curtailment of support for Linux means that any application needing Adobe Air may not work on a more current Linux distribution. That affects Zinio, so I'll be retaining a Debian 6 instance for a while yet, unless a bout of testing reveals that a move to the newer version is possible. As for Dropbox, I am sure that I can recall why I moved it onto Debian, but it's working well on there so I am in no hurry to move it over either. There are times when slower software development cycles are better...

Using a variant of Debian's Iceweasel that keeps pace with Firefox

5^th February 2013

Left to its own devices, Debian will leave you with an ever ageing re-branded version of Firefox that was installed at the same time as the rest of the operating system. From what I have found, the main cause of this was that Mozilla's wanting to retain control of its branding and trademarks in a manner not in keeping with Debian's Free Software rules. This didn't affect just Firefox but also Thunderbird, Sunbird and Seamonkey with Debian's equivalents for these being IceDove, IceOwl and IceApe, respectively.

While you can download a tarball of Firefox from the web and use that, it'd be nice to get a variant that updated through Debian's normal apt-get channels. In fact, IceWeasel does get updated whenever there is a new release of Firefox, even if these updates never find their way into the usual repositories. While I have been known to take advantage of the more frozen state of Debian compared with other Linux distributions, I don't mind getting IceWeasel updated so it isn't a security worry.

The first step in so doing is to add the following lines to /etc/apt/sources.list using root access (using one of sudo, gksu or su to assume root privileges) since the file normally cannot be edited by normal users:

deb http://backports.debian.org/debian-backports squeeze-backports main deb http://mozilla.debian.net/ squeeze-backports iceweasel-release

With the file updated and saved, the next step is to update the repositories on your machine using the following command:

sudo apt-get update

With the above complete, it is time to overwrite the existing IceWeasel installation with the latest one using an apt-get command that specifies the squeeze-backports repository as its source using the -t switch. While IceWeasel is installed from the iceweasel-release squeeze-backports repository, there are dependencies that need to be satisfied and these come from the main squeeze-backports one. The actual command used is below:

sudo apt-get install -t squeeze-backports iceweasel

While that was all that I needed to do to get IceWeasel 18.0.1 in place, some may need the pkg-mozilla-archive-keyring package installed too. For those needing extra information beyond what's here, there's always the Debian Mozilla team.

Removing VMware Player from Linux Mint Debian Edition

4^th August 2012

A whole slew of updates has appeared for my Linux Mint Debian Edition PC. However, to instate them, I needed to remove VMware Player and this is the command to do so:

sudo vmware-installer -u vmware-player

It worked in my case, and my system updates are in progress as I write this. The same command should work for other Linux distros where VMware Player was installed using the *.bundle installer. VMware Player remains in place on my main PC though, so I am not ditching it just yet, even if I have to be careful when running it on Linux Mint 13 so as not to freeze the system on myself.

Changing from to Nvidia Graphics Drivers on Linux Mint Debian Edition 64-bit

22^nd April 2012

One way of doing this is to go to the Nvidia website and download the latest file from the relevant page on there. Then, the next stage is to restart your PC and choose rescue mode instead of the more usual graphical option. This drops you onto a command shell that is requesting your root password. Once this is done, you can move onto the next stage of the exercise. Migrate to the directory where the *.run file is located and issue a command similar to the following:

bash NVIDIA-Linux-x86_64-295.40.run

The above was the latest file available at the time of writing, which may have changed by the time that you read this. If the executable asks to modify your X configuration file, I believe that the best course is to let it do that. Editing it yourself or running nvidia-xconfig are alternative approaches if you so prefer.

Since proprietary Nvidia drivers are included in the repositories for Linux Mint Debian Edition, that may be a better course of action since you will get updates through normal system update channels. Then, the course of action is to start by issuing the following installation commands:

sudo apt-get install module-assistant sudo apt-get install nvidia-kernel-common sudo apt-get install nvidia-glx sudo apt-get install kernel-source-NVIDIA sudo apt-get install nvidia-xconfig

Once those have completed, issuing the following in turn will complete the job ahead of a reboot:

sudo m-a a-i nvidia sudo modprobe nvidia sudo nvidia-xconfig

If you reboot before running the above like I did, you will get a black screen with a flashing cursor instead of a full desktop because X failed to load. Then, the remedy is to reboot the machine and choose the rescue mode option, provide the root password and issue the three commands (at this point, the sudo prefix can be dropped because it's unneeded) then. Another reboot will see order restored and the new driver in place. Running the following at that point will do a check on things, as will be the general appearance of everything:

glxinfo | grep render

Synchronising package selections between Linux Mint and Linux Mint Debian Edition

18^th April 2012

To generate the package list on the GNOME version of Linux Mint, I used the Backup Tool. It simply was a matter of using the Backup Software Selection button and telling it where to put the file that it generates. Alternatively, dpkg can be used from the command line like this:

sudo dpkg --get-selections > /backup/installed-software.txt

After transferring the file to the machine with Linux Mint Debian Edition, I tried using the Backup Tool on there too. However, using the Restore Software Selection button and loading the required only produced an irrecoverable error. Therefore, I set to looking around the web and found a command line approach that did the job for me.

The first step is to load the software selection using dpkg by issuing this command (it didn't matter that the file wasn't made using the dpkg command, though I suspect that's what the Linux Mint Backup Tool was doing that behind the scenes):

sudo dpkg --set-selections < /backup/installed-software.txt

Then, I started dselect and chose the installation option from the menu that appeared. The first time around, it fell over but trying again was enough to complete the job. Packages available to the vanilla variant of Linux Mint but not found in the LMDE repositories were overlooked as I had hoped, and installation of the extra packages had no impact on system stability either.

sudo dselect

Apparently, there is an alternative to using dselect that is based on the much used apt-get command, but I didn't make use of it so cannot say more:

sudo apt-get dselect-upgrade

All that I can say is that the dpkg/dselect combination did what I wanted, so I'll keep them in mind if ever need to synchronise software selections between two Debian-based distributions in the future again. While the standard edition of Linux Mint may be based on Ubuntu rather than Debian, Ubuntu is itself based on Debian. Thus, the description holds here.

Uninstalling VirtualBox Guest Additions on a Linux Guest OS

8^th April 2012

Within the last few days, I updated my Linux Mint Debian Edition virtual machine installation to Update 4. Between not following the instructions so closely and problems with the update server, a re-installation preceded the update itself. When all was done, no desktop environment appeared, and issuing the startx command revealed that it was one of the VirtualBox drivers that was the cause of the problem. With my being unable to see any files on the VirtualBox virtual CD, something else needed doing and the executing following command (replacing [VboxAddonsFolder] with VBoxGuestAdditions-4.1.12 in my case, but it is different for each VirtualBox version) resolved the situation:

/opt/[VboxAddonsFolder]/uninstall.sh

When it was complete, a scrambled desktop began to appear, so a reboot was to set things to rights. Then, I could set to looking at what Update 4 had brought to Linux Mint Debian Edition.

How the Cinnamon desktop environment offers a conventional alternative to the experimental approaches of others

28^th January 2012

The computer on which I am writing these words is running Linux Mint with the Cinnamon desktop environment, a fork of GNOME Shell. This looks as if it will be the default face of GNOME 3 in the next version of Linux Mint, with the MGSE dressing up of GNOME Shell looking more and more like an interim measure until something more consistent was available. While some complained that what was delivered in version 12 of the distribution was a sort of greatest hits selection, I reckon that bets were being hedged by the project team.

Impressions of what's coming

By default, you get a single panel at the bottom of your screen with everything you need in there. However, it is possible to change the layout so that the panel is at the top or there are two panels, one at the top and the other at the bottom. So far, there is no means of configuring which panel applet goes where, as was the case in Linux Mint 11 and its predecessors. However, the default placements are very sensible, so I have no cause for complaint at this point.

Just because you cannot place applets doesn't mean that there is no configurability, though. Since Cinnamon is extensible, you can change the way that time is displayed in the clock, as well as enabling additional applets. It is also possible to control visual effects, such as the way new application windows pop up on a screen.

GNOME 3 is there underneath all of this, though there's no sign of the application dashboard of GNOME Shell. The continually expanding number of slots in the workspace launcher is one sign, as is the enabling of a hotspot at the top right hand corner by default. This brings up an overview screen showing what application windows are open in a workspace. The new Mint menu even gets the ability to search through installed applications, together with the ability to browse through what's available.

In summary, Cinnamon already looks good, though a little polish and extra configuration options wouldn't go amiss. An example of the former is the placement of desktop numbers in the workspace switcher, and I already have discussed the latter. It does appear that the Linux Mint approach to desktop environments is taking shape with a far more conventional feel than the likes of Unity or GNOME Shell. Just as Cinnamon has become available in openSUSE, I can see it gracing LMDE too whenever Debian gets to moving over to GNOME 3 as must be inevitable now unless they take another approach such as MATE.

In comparison with a revolution

While Linux Mint are choosing convention and streamlining GNOME to their own designs, it appears that Ubuntu's Unity is getting ever more experimental as the time when Ubuntu simply evolved from one release to the next becomes an increasingly more distant memory. The latest development is the announcement that application menus could get replaced by a heads-up display (HUD) instead. That would be yet another change made by what increasingly looks like a top-down leadership, reminiscent of what exists at Apple. While it is good to have innovation, you have to ask where users fit in all of this when Linux Mint already has gained from what has been done so far and may gain more again. Still, seeing what happens to Ubuntu sounds like an interesting pastime, though I'm not sure that I'd be depending on the default spin of this distro as my sole operating system right now. Also, changing the interface every few months wouldn't work in a corporate environment at all, so you have to wonder where Mark Shuttleworth is driving all this, though Microsoft is engaging in a bit of experimentation of its own. We are living in interesting times for the computer desktop, so it's just as well that there are safe havens like Linux Mint, too. Watching from afar sounds safer.

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