Technology Tales

Adventures & experiences in contemporary technology

Controlling display of users on the logon screen in Linux Mint 20.3

15th February 2022

Recently, I tried using Commento with a static website that I was developing and this needed PostgreSQL rather than MySQL or MariaDB, which many content management tools use. That meant a learning curve that made me buy a book as well as the creation of a system account for administering PostgreSQL. These are not the kind of things that you want to be too visible so I wanted to hide them.

Since Linux Mint uses AccountsService, you cannot use lightdm to do this (the comments in /etc/lightdm/users.conf suggest as much). Instead, you need to go to /var/lib/AccountsService/users and look for a file called after the user name. If one exists, all that is needed is for you to add the following line under the [User] section:

SystemAccount=true

If there is no file present for the user in question, then you need to create one with the following lines in there:

[User]
SystemAccount=true

Once the configuration files are set up as needed, AccountsService needs to be restarted and the following command does that deed:

sudo systemctl restart accounts-daemon.service

Logging out should reveal that the user in question is not listed on the logon screen as required.

Stopping Firefox from launching on the wrong virtual desktop on Linux Mint

12th October 2021

During the summer, I discovered that Firefox was steadfastly opening on the same virtual desktop on Linux Mint (the Cinnamon version) regardless of the one on which it was started. Being a creature of habit who routinely opens Firefox within the same virtual desktop all the time, this was not something that I had noticed until the upheaval of a system rebuild. The supposed cause is setting the browser to reopen tabs from the preceding session. The settings change according to the version of Firefox but it is found in Settings > General in the version in which I am writing these words (Firefox Developer Edition 94.0b4) and the text beside the tick box is Open previous windows and tabs.

While disabling the aforementioned setting could work, there is another less intrusive solution. This needs the opening of a new tab and the entering of the address about:config in the address bar. If you see a warning message about the consequences of proceed further, accept responsibility using the interface as you do just that. In the resulting field marked Search preference name, enter the text widget.disable-workspace-management and toggle the setting from false to true in order to activate it. Then, Firefox should open on the desktop where you want it and not some other default location.

Getting rid of the Windows Resizing message from a Manjaro VirtualBox guest

27th July 2020

Like Fedora, Manjaro also installs a package for VirtualBox Guest Additions when you install the Linux distro in a VirtualBox virtual machine. However, it does have certain expectations when doing this. On many systems and my own is one of these, Linux guests are forced to use the VMSVGA virtual graphics controller while Windows guests are allowed to use the VBoxSVGA one. It is the latter that Manjaro expects so you get a message like the following appearing when the desktop environment has loaded:

Windows Resizing
Set your VirtualBox Graphics Controller to enable windows resizing

After ensuring that gcc, make, perl and kernel headers are installed, I usually install VirtualBox Guest Additions myself from the included ISO image and so I did the same with Manjaro. Doing that and restarting the virtual machine got me extra functionality like screen resizing and being able to copy and paste between the VM and elsewhere after choosing the Bidirectional setting in the menus under Devices > Shared Clipboard.

That still left an unwanted message popping up on startup. To get rid of that, I just needed to remove /etc/xdg/autostart/mhwd-vmsvga-alert.desktop. It can be deleted but I just moved it somewhere else and a restart proved that the message was gone as needed. Now everything is working as I wanted.

Restoring the menu bar on GNOME Terminal in a GNOME Shell session

25th July 2020

By default, a GNOME Terminal instance does not display a menu bar and that applies not only in GNOME Shell but also on the Cinnamon Desktop environment. In the latter, it is easy enough to display the menu bar using the context menu produced by right clicking in the window before going to Edit > Preferences and ticking the box for Show menubar by default in new terminals in the General section. After closing the Preferences dialogue, every new GNOME Terminal session will show the menu bar.

Unfortunately, it is not so easy in GNOME Shell though the context menu route does allow you to unhide the menu bar on a temporary basis. That is because the requisite tickbox is missing from the Preferences dialogue box displayed after navigating to Edit > Preferences in the menus. To address, you need the execute the following command in a terminal session:

gsettings set org.gnome.Terminal.Legacy.Settings headerbar false

This not only adds the menu bar on a permanent basis but it also adds the missing tickbox, populated as required. GNOME Shell may be minimalist in some ways but making this action harder looks like going a little too far.

Lessons learned on managing Windows Taskbar and Start Menu colouring in VirtualBox virtual machines

9th December 2019

In the last few weeks, I have had a few occasions when the colouration of the Windows 10 taskbar and its Star Menu has departed from my expectations. At times, this happened in VirtualBox virtual machine installations and both the legacy 5.2.x versions and the current 6.x ones have thrown up issues.

Lessons learned on managing Windows Taskbar and Start Menu colouring in VirtualBox virtual machines

Lessons learned on managing Windows Taskbar and Start Menu colouring in VirtualBox virtual machines

The first one actually happened with a Windows 10 installation in VirtualBox 5.2.x when the taskbar changed colour to light grey and there was no way to get it to pick up the colour of the desktop image to become blue instead. The solution was to change the Windows from Light to Dark in order for the desired colouration to be applied and the settings above are taken from the screen that appears on going to Settings > Personalisation > Colours.

The second issue appeared in Windows 10 Professional installation in VirtualBox 6.0.x when the taskbar and Start Menu turned transparent after an updated. This virtual machine is used to see what is coming in the slow ring of Windows Insider so some rough edges could be expected. The solution here was to turn off 3D acceleration in the Display pane of the VM settings after shutting it down. Starting it again showed that all was back as expected.

Both resolutions took a share of time to find and there was a deal of experimentation needed too. Once identified, they addressed the issues as desired so I am recording here for use by others as much as future reference for myself.

Creating a VirtualBox virtual disk image using the Linux command line

9th September 2019

Much of the past weekend was spent getting a working Debian 10 installation up and running in a VirtualBox virtual machine. Because I chose the Cinnamon desktop environment, the process was not as smooth as I would have liked so a minimal installation was performed before I started to embellish as I liked. Along the way, I got to wondering if I could create virtual hard drives using the command line and I found that something like the following did what was needed:

VBoxManage createmedium disk --filename <full path including file name without extension> -size <size in MiB> --format VDI --variant Standard

Most of the options are self-explanatory part from the one named variant. This defines whether the VDI file expands to the maximum size specified using the size parameter or is reserved with the size defined in that parameter. Two VDI files were created in this way and I used these to replace their Debian 8 predecessors and even to save a bit of space too. If you want, you can find out more in the user documentation but this post hopefully gets you started anyway.

Lightening of desktop background images on Linux Mint Debian Edition running in Virtualbox

22nd October 2018

After a recent upgrade to Linux Mint Debian Edition 3 in a VirtualBox virtual machine that I had running its predecessor, I began to notice that background images were being loaded with more washed out of faded colours. This happened at startup so selecting another background image worked as intended until the same thing happened to that after a system restart.

This problem is not new and has affected the Cinnamon desktop in the main Linux Mint variant (the one that is based on Ubuntu) and issuing the following command in a terminal session is a suggested solution:

gsettings set org.cinnamon.muffin background-transition fade-in

In my case, that solved the problem and desktop background image display is as it should be since I executed the above. All it took was a change to a system setting.

Quickly changing between virtual desktops in Windows 10

12th October 2018

One of the benefits of running Linux is the availability of virtual desktops and installing VirtuaWin was the only way to get the same functionality in Windows before the launch of Windows 10. For reasons known to Microsoft, they decided against the same sort of implementation as seen in Linux or UNIX. Instead, they put the virtual desktop functionality a click away and rather hides it from most users unless they know what clicking on the Task View button allows. The approach also made switching between desktops slower with a mouse. However, there are keyboard shortcuts that addresses this once multiple virtual desktops exist.

Using WIN+CTRL+LEFT or WIN+CTRL+RIGHT does this easily once you have mastered the action. Depending on your keyboard setup, WIN is the Windows, Super or Command key while CTRL is the Control key. Then, LEFT is the left arrow key and RIGHT is the right arrow key. For machines with smaller screens where multi-tasking causes clutter, virtual desktops are a godsend for organising how you work and having quick key combinations for switching between them adds to their utility.

Rethinking photo editing

17th April 2018

Photo editing has been something that I have been doing since my first-ever photo scan in 1998 (I believe it was in June of that year but cannot be completely sure nearly twenty years later). Since then, I have been using a variety of tools for the job and wondered how other photos can look better than my own. What cannot be excluded is my preference for being active in the middle of the day when light is at its bluest as well as a penchant for using a higher ISO of 400. In other words, what I do when making photos affects how they look afterwards as much as the weather that I had encountered.

My reason for mentioning the above aspects of photographic craft is that they affect what you can do in photo editing afterwards, even with the benefits of technological advancement. My tastes have changed over time, so the appeal of re-editing old photos fades when you realise that you only are going around in circles and there always are new ones to share, so that may be a better way to improve.

When I started, I was a user of Paint Shop Pro but have gone over to Adobe since then. First, it was Photoshop Elements, but an offer in 2011 lured me into having Lightroom and the full version of Photoshop. Nowadays, I am a Creative Cloud photography plan subscriber so I get to see new developments much sooner than once was the case.

Even though I have had Lightroom for all that time, I never really made full use of it and preferred a Photoshop-based workflow. Lightroom was used to select photos for Photoshop editing, mainly using adjustments for such things as tones, exposure, levels, hue and saturation. Removal of dust spots, resizing and sharpening were other parts of a still minimalist approach.

What changed all this was a day spent pottering about the 2018 Photography Show at the Birmingham NEC during a cold snap in March. That was followed by my checking out theĀ Adobe YouTube Channel afterwards where there were videos of the talks featured every day of the four-day event. Here are some shortcuts if you want to do some catching up yourself: Day 1, Day 2, Day 3, and Day 4. Be warned though that these videos are long in that they feature the whole day and there are enough gaps that you may wish to fast-forward through them. Even so, there is quite a bit of variety of things to see.

Of particular interest were the talks given by the landscape photographer David Noton who sensibly has a philosophy of doing as little to his images as possible. It helps that his starting points are so good that adjusting black and white points with a little tonal adjustment does most of what he needs. Vibrancy, clarity and sharpening adjustments are kept to a minimum while some work with graduated filters evens out exposure differences between skies and landscapes. It helps that all this can be done in Lightroom, so that set me thinking about trying it out for size and the trick of using the backslash (\) key to switch between raw and processed views is a bonus granted by non-destructive editing. Others may have demonstrated the creation of composite imagery, but simplicity is more like my way of working.

Confusingly, we now have the cloud-based Lightroom CC while the previous desktop counterpart is known as Lightroom Classic CC. Though the former may allow for easy dust spot removal among other things, it is the latter that I prefer because the idea of wholesale image library upload does not appeal to me for now and I already have other places for off-site image backup like Google Drive and Dropbox. The mobile app does look interesting since it allows capturing images on a such a device in Adobe’s raw image format DNG. Still, my workflow is set to be more Lightroom-based than it once was and I quite fancy what new technology offers, especially since Adobe is progressing its Sensai artificial intelligence engine. The fact that it has access to many images on its systems due to Lightroom CC and its own stock library (Adobe Stock, formerly Fotolia) must mean that it has plenty of data for training this AI engine.

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

29th May 2014

There are times when you might need to drop back to a full screen terminal session from a graphical desktop environment when running Linux. One example that I have encountered is the installation of Nvidia’s own graphics drivers on either Ubuntu or Linux Mint. Another happened to me on Arch Linux when a Cinnamon desktop environment update left me without the ability to open up a terminal window. Then, the full screen command allowed me to add in an alternative terminal emulator and Tech Drive-in’s list came in handy for this. there might have been something to sort on a FreeBSD installation that needed the same treatment. This latter pair happened to me on sessions running within VirtualBox and that has its own needs when it comes to dropping into a full screen command line session and I will come to that later.

When running Linux on a physical PC, the keyboard shortcuts that you are CTRL + ALT + F1 for entering a full screen terminal session and CTRL + ALT + F7 for returning to the graphical desktop again. When you are running a Linux guest in VirtualBox and the host operating system also is Linux, then the aforementioned shortcuts do not work within the virtual machine but instead affect the host. To get the guest operating system to drop into a full screen terminal session, the keyboard shortcut you need is [Host Key] + F1 and the default host key is the right hand CTRL key on your keyboard unless you have assigned to something else as I have. The exit the full screen terminal session and return to the graphical desktop again, the keyboard shortcut is [Host Key] + F7.

All of this works with GNOME and Cinnamon desktop environments running in X sessions and I cannot vouch for anything else unless alternatives like Wayland come my way. Hopefully, this useful functionality applies to those other set-ups too because there are times when a terminal session is needed to recover from a mishap, rare though those thankfully are and they need to be very rare if not non-existent for most users.

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