Technology Tales

Dropping back to a full screen terminal session from a desktop one in Linux

29^th May 2014

There are times when you might need to access a full screen terminal from a Linux graphical desktop. For example, I have needed this when installing Nvidia's graphics drivers on Ubuntu or Linux Mint. Another instance occurred on Arch Linux when a Cinnamon desktop update prevented me from opening a terminal window. The full screen command let me install an alternative terminal emulator, with Tech Drive-in's list proving helpful. Similar issues might need fixing on FreeBSD installations. These latter examples happened within VirtualBox, which has special requirements for accessing full screen command line sessions, which I'll explain later.

When running Linux on a physical PC, press CTRL + ALT + F1 to enter a full screen terminal and CTRL + ALT + F7 to return to the graphical desktop. In a Linux VirtualBox guest with a Linux host, these shortcuts affect the host instead. For the guest OS, use [Host Key] + F1 to enter a full screen terminal and [Host Key] + F7 to return to the graphical desktop. The default Host Key is the right CTRL key, unless you've changed it.

X sessions in GNOME and Cinnamon desktop environments support this functionality, but I can't confirm it works with alternatives like Wayland. Hopefully, this feature extends to other setups, as terminal sessions are occasionally needed for system recovery. Such mishaps are thankfully rare and should be virtually non-existent for most users.

Fixing Background Image Display in GNOME Shell 3.10

2^nd May 2014

On upgrading from Ubuntu GNOME 13.10 to Ubuntu GNOME 14.04, a few rough edges were to be noticed. One was the display of my chosen background image: it was garbled. Later, I discovered that there is a maximum width of 2560 px for background images in GNOME Shell these days and that things get messy beyond that.

In my case, the image width was around 6000 px, and I was used to it getting resized in GNOME Shell 3.8 and its predecessors. It appears that the functionality got removed after that though, so the workaround of manual image resizing in the GIMP needed to be employed. Though having big images open in memory creates an additional overhead, not handling them very well at all looks like a bug caused by setting 2560 px as a maximum screen width for the GNOME Shell panel and the complete removal of Nautilus from desktop rendering duties. Let's hope that sense is seen with ever larger screen sizes and resolutions coming our way.

It's the sort of thing that did get me looking at adding on Cinnamon 2.2 for a while before setting background image scaling using the indispensable GNOME Tweak Tool was discovered. LinuxG.net has a useful tutorial on this for anyone with such an adventurous streak in them. For now though, I am OK with my set-up but the GNOME project's focus on minimalism could affect us in other ways, so I can see why Clem Lefebvre started the Cinnamon one primarily for Linux Mint and the desktop environment is appearing elsewhere too. After all, Gedit lost its menu bar in GNOME 3.12 so it's just as well that we have alternatives.

Update 2014-05-06: It appears that the desktop image bug that afflicts GNOME Shell 3.10 got sorted for GNOME Shell 3.12. At least, that is the impression that an Antergos instance in a VirtualBox virtual machine gives me.

ERROR: Can't find the archive-keyring

10^th April 2014

When I recently did my usual system update for the stable version Ubuntu GNOME, there were some updates pertaining to apt and the process failed when I executed the following command:

sudo apt-get upgrade

Usefully, some messages were issued and here's a flavour:

Setting up apt (0.9.9.1~ubuntu3.1) ... ERROR: Can't find the archive-keyring Is the ubuntu-keyring package installed? dpkg: error processing apt (--configure): subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing: apt E: Sub-process /usr/bin/dpkg returned an error code (1)

Web searches indicated the issue was missing files in /usr/share/keyring, which I didn't delete. Since apt was disabled due to the missing keyring files, installing software for fixes was impossible. My solution was to copy the /usr/share/keyring files from an Ubuntu GNOME 14.04 virtual machine to the same location on my Ubuntu GNOME 13.10 host. For others without this setup, I've included these files in a zip file below. While other solutions like Y PPA were mentioned, they required prior installation, making them useless when tools like Synaptic were unavailable. I'd appreciate information on other fixes that don't involve reinstalling the operating system, potential causes for the file loss, and how to prevent it.

Ubuntu Keyrings

Sorting out a system update failure for FreeBSD

3^rd April 2014

With my tendency to apply Linux updates using the command, I was happy to see that something similar was possible in FreeBSD too. The first step is to fire up a terminal session and drop into root using the su command. That needs the root superuser password to continue, and the next step is to update the local repositories using the following command:

pkg update

After that, it is time to download updated packages and install these by issuing this command:

pkg upgrade

Most of the time, that is sufficient, but I discovered that there are times when the above fails and additional interventions are needed. What I had uncovered were dependency error messages, and I set to looking around the web for remedies to this. One forum question that was similar to what I had met with the suggestion of consulting the file called UPDATING in /usr/ports/. An answer like that looks unhelpful, but for the inclusion of advice where extra actions were needed. Also, there is a useful article on updating FreeBSD ports that gives more in the way of background knowledge so you understand the more about what needs doing.

Following both that and the UPDATING file resulted in my taking the following sequence of steps. The first act was to download and initialise the Ports Collection, a set of build instructions.

portsnap fetch extract

The above is a one time only action, so future updates are done as follows:

portsnap fetch update

With an up to date Ports Collection in place, it was time to install portman:

pkg install portman

A look through /usr/ports/UPDATING revealed the commands I needed for updating Python and Perl to address the dependency problem that I was having:

portmaster -o devel/py-setuptools27 devel/py-setuptools portmaster -r py\*setuptools

With those completed, I re-ran pkg update again and all was well. The extra actions needed to get that result will not get forgotten, and I am sharing them on here so I know where they are. If anyone else has use for them, that would be even better.

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.

The bold gamble behind Linux Voice magazine

1^st March 2014

During the latter part of last year, the magazine Linux Format suffered a staff clear-out, and I was left wondering why. It was as if a load of folk left at once and, even if I have seen that sort of thing happening at my current place of work, I was asking if something went wrong at Future Publishing. Instead, I had missed the fact that the former Linux Format staff were starting their own magazine. They crowdfunded it on Indiegogo. It took the appearance of Linux Voice on a shelf in the Macclesfield WHSmith's for me to become enlightened about this.

It seems risky for a whole team from one publisher's magazine to leave and create their own similar publication, especially given the current instability of magazine publishing in the digital age. The mention of a non-compete agreement reminded me of my own workplace. Their former employers' reaction would be interesting to know, as mine might consider legal action if I did something similar, assuming it were possible; I too would be bound by a six-month non-compete clause after leaving.

Regarding the magazine's content, it is appropriately good. While occasional misspellings might occur, articles on OwnCloud and Arch Linux installation, along with reviews of Mageia 4 and FreeBSD 10, would interest me. Many familiar names from Linux Format are also present, creating a sense of continuity. The new magazine's design is less extravagant than its established competitor, and their coexistence will be worth observing.

New ideas take time to develop, and I wish the new magazine success. Its goals are positive: half of its profits will support open-source software, and articles will be openly accessible via a Creative Commons licence. However, its immediate financial stability is crucial, making the next few months significant. The experienced team behind the magazine is a strong asset and could prevent it from becoming like Walking World Ireland and Cycling World, which appear irregularly in stores. The support of an enthusiastic community is also beneficial. I might eventually have to choose between Linux Voice and Linux Format, similar to my choice between Linux Magazine and Linux User & Developer. Despite being a niche operating system, Linux users have a good selection of magazines.

Some SAS Macro code for detecting the presence or absence of a variable in a dataset

4^th December 2013

Recently, I needed to put in place some code to detect the presence or absence of a variable in a dataset, and I chose SAS Macro programming as the way to do what I wanted. The logic was based on a SAS sample that achieved the same result in a data step and some code that I had for detecting the presence or absence of a dataset. Mixing the two together gave me something like the following:

%macro testvar(ds=,var=);

%let dsid=%sysfunc(open(&ds,in)); %let varexist=%sysfunc(varnum(&dsid,&var)); %if &dsid > 0 %then %let rc=%sysfunc(close(&dsid));

%if &varexist gt 0 %then %put Info: Variable &var is in the &ds dataset; %else %put Info: Variable &var is not in the &ds dataset;

%mend testvar;

%testvar(ds=dataset,var=var);

What this does is open up a dataset and look for the variable number in the dataset. In datasets, variables are numbered from left to right with 1 for the first one, 2 for the second and so on. If the variable is not in the dataset, the result is 0 so you know that it is not there. All of this is what the VARNUM SCL function within the SYSFUNC macro function does. In the example, this resolves to %sysfunc(varnum(&dsid,var)) with no quotes around the variable name, akin to what you would do in data step programming. Once you have the variable number or 0, then you can put in place some conditional logic that makes use of the information, like what you see in the above simple example. Of course, that would be expanded to something more useful in real life, but I hope it helps to show you the possibilities here.

A fallback method of installing Nightingale in Linux

3^rd December 2013

When I upgraded to Ubuntu GNOME 13.10 and went for the 64-bit variant, I tried a previously tried and tested approach for installing Nightingale that used a PPA, only for it not to work. At that point, the repository had not caught up with the latest Ubuntu release (it has by the time of writing) and other pre-compiled packages would not work either. However, there was one further possibility left, and that was downloading a copy of the source code and compiling that. My previous experiences of doing that kind of thing have not been universally positive, so it was not my first choice, but I gave it a go anyway.

To get the source code, I first needed to install Git so I could take a copy from the version controlled repository and the following command added the tool and all its dependencies:

sudo apt-get install git autoconf g++ libgtk2.0-dev libdbus-glib-1-dev libtag1-dev libgstreamer-plugins-base0.10-dev zip unzip

With that lot installed, it was time to check out a copy of the latest source code, and I went with the following:

git clone https://github.com/nightingale-media-player/nightingale-hacking.git

The next step was to go into the nightingale-hacking sub-folder and issue the following command:

./build.sh

That should produce a subdirectory named nightingale that contains the compiled executable files. If this exists, it can be copied into /opt. If not, then create a folder named nightingale under /opt using copy the files from ~/nightingale-hacking/compiled/dist into that location. Ubuntu GNOME 13.10 comes with GNOME Shell 3.8, the next step took a little fiddling before it was sorted: adding an icon to the application menu or dashboard. This involved adding a file called nightingale.desktop in /usr/share/applications/ with the following contents:

[Desktop Entry] Name=Nightingale Comment=Play music TryExec=/opt/nightingale/nightingale Exec=/opt/nightingale/nightingale Icon=/usr/share/pixmaps/nightingale.xpm Type=Application X-GNOME-DocPath=nightingale/index.html X-GNOME-Bugzilla-Bugzilla=Nightingale X-GNOME-Bugzilla-Product=nightingale X-GNOME-Bugzilla-Component=BugBuddyBugs X-GNOME-Bugzilla-Version=1.1.2 Categories=GNOME;Audio;Music;Player;AudioVideo; StartupNotify=true OnlyShowIn=GNOME;Unity; Keywords=Run; Actions=New X-Ubuntu-Gettext-Domain=nightingale

[Desktop Action New] Name=Nightingale Exec=/opt/nightingale/nightingale OnlyShowIn=Unity

It was created from a copy of another *.desktop file and the categories in there together with the link to the icon were as important as the title and took a little tinkering before all was in place. Also, you may find that /opt/nightingale/chrome/icons/default/default.xpm needs to be become /usr/share/pixmaps/nightingale.xpm using the cp command before your new menu entry gains an icon to go with it. While the steps that I describe here worked for me, there is more information on the Nightingale wiki if you need it.

Wiping of hard drives with Linux

2^nd December 2013

More than a decade of computer upgrades can leave obsolete kit in your hands, while legislation on electronic waste disposal might leave you wondering how to get rid of it. Thankfully, I discovered that my local council refuse site, only a few miles away, accepts such items for recycling. It saw me several times last summer disposing of obsolete and non-working gadgets that had stayed with me too long. Some were as bulky as computer monitors and printers, while others were relatively small.

Disposing of non-working, obsolete equipment is an easy choice, but it's harder when a device still works and might be useful. Computer motherboards still include PS/2, floppy and IDE ports, making decisions trickier. My Gigabyte Z87-HD3 mainboard has one PS/2 port (compared to two on older boards), limited IDE sockets and surprisingly, a floppy drive socket, unexpected for anyone who considers these technologies outdated. PC technology isn't abandoning backwards compatibility yet, as this mainboard supports an Intel Core i5-4670K CPU and 24 GB of RAM.

Despite the IDE port, I wasn't tempted to use my leftover 10 GB and 20 GB hard drives that I've had for over a decade. Ten years ago, that capacity would have been respectable if not for our growing need for data storage due to photography, video and music. Beyond size limitations, these drives' speed can't compare with today's standards, which became obvious when I replaced a similarly aged Samsung 160 HD with a Samsung SSD.

This line of thought led me to recycle the drives, so I considered wiping them. Linux offers a good tool for this: the dd command. It can overwrite disk data to make information virtually irretrievable. Linux also has several dummy devices that supply junk data for overwriting. These work like /dev/null, which suppresses command output. The first is /dev/zero, which supplies octal zeros, which I used. For those wanting more randomness in overwriting, there's also /dev/random and /dev/urandom.

To overwrite data on a disk with zeroes while having feedback on progress, the following command achieves the required result:

sudo dd if=/dev/zero | pv | sudo dd of=/dev/sdd bs=16M

The operation needs root privileges. The if parameter of dd specifies the input data, which is sent to pv that displays a progress bar not provided by dd alone. The output then goes to another dd command with the target disk specified by the of parameter. The bs parameter in the second dd command sets the block size for writing. Note that pv isn't installed by default. On Debian, Ubuntu or Linux Mint systems, install it with this command:

sudo apt-get install pv

The pv sandwich is also invaluable when using dd to copy partitions between different physical or virtual disks. Without it, you might wonder what's happening during silent operations, which is particularly concerning when retrying failed operations that take a long time to complete.

Setting up a WD My Book Live NAS on Ubuntu GNOME 13.10

1^st December 2013

The official line from Western Digital is this: they do not support the use of their My Book Live NAS drives with Linux or UNIX. However, what that means is that they only develop tools for accessing their products for Windows and maybe OS X. It still doesn't mean that you cannot access the drive's configuration settings by pointing your web browser at http://mybooklive.local/. In fact, not having those extra tools is no drawback at all since the drive can be accessed through your file manager of choice under the Network section and the default name is MyBookLive too, so you easily can find the thing once it is connected to a router, or switch anyway.

Once you are in the server's web configuration area, you can do things like changing its name, updating its firmware, finding out what network has been assigned to it, creating and deleting file shares, password protecting file shares and other things. These are the kinds of things that come in handy if you are going to have a more permanent connection to the NAS from a PC that runs Linux. The steps that I describe have worked on Ubuntu 12.04 and 13.10 with the GNOME desktop environment.

What I was surprised to discover that you cannot just set up a symbolic link that points to a file share. Instead, it needs to be mounted and this can be done from the command line using mount or at start-up with /etc/fstab. For this to happen, you need the Common Internet File System utilities and these are added as follows if you need them (check in the Software Centre or in Synaptic):

sudo apt-get install cifs-utils

Once these are added, you can add a line like the following to /etc/fstab:

//[NAS IP address]/[file share name] /[file system mount point] cifs credentials=[full file location]/.creds, iocharset=utf8, sec=ntlm, gid=1000, uid=1000, file_mode=0775, dir_mode=0775 0 0

Though I have broken it over several lines above, this is one unwrapped line in /etc/fstab with all the fields in square brackets populated for your system and with no brackets around these. Though there are other ways to specify the server, using its IP address is what has given me the most success; this is found under Settings > Network on the web console. Next up is the actual file share name on the NAS; I have used a custom term instead of the default of Public. The NAS file share needs to be mounted to an actual directory in your file system like /media/nas or whatever you like; however, you will need to create this beforehand. After that, you have to specify the file system, and it is cifs instead of more conventional alternatives like ext4 or swap. After this and before the final two space delimited zeroes in the line comes the chunk that deals with the security of the mount point.

What I have done in my case is to have a password-protected file share and the user ID and password have been placed in a file in my home area with only the owner having read and write permissions for it (600 in chmod-speak). Preceding the filename with a "." also affords extra invisibility. That file then is populated with the user ID and password like the following. Of course, the bracketed values have to be replaced with what you have in your case.

username=[NAS file share user ID] password=[NAS file share password]

With the credentials file created, its options have to be set. First, there is the character set of the file (usually UTF-8 and I got error code 79 when I mistyped this) and the security that is to be applied to the credentials (ntlm in this case). To save having no write access to the mounted file share, the uid and gid for your user needs specification, with 1000 being the values for the first non-root user created on a Linux system. After that, it does no harm to set the file and directory permissions because they only can be set at mount time; using chmod, chown and chgrp afterwards, has no effect whatsoever. Here, I have set permissions to read, write and execute for the owner and the user group while only allowing read and execute access for everyone else (that's 775 in the world of chmod).

All of what I have described here worked for me and had to be gleaned from disparate sources like Mount Windows Shares Permanently from the Ubuntu Wiki, another blog entry regarding the permissions settings for a CIFS mount point and an Ubuntu forum posting on mounting CIFS with UTF-8 support. Because of the scattering of information, I just felt that it needed to all together in one place for others to use, and I hope that fulfils someone else's needs similarly to mine.

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