An old UVC webcam is not recognised

The problem: When I plugged an old UVC webcam into a USB port, no new device /dev/video[num] was created, and neither Skype nor guvcview displayed it as a camera to choose from in the settings.

The solution: Install the "uvcdynctrl" package (on Fedora 27) with sudo dnf install uvcdynctrl. Reinsert the camera's plug into the USB slot.

Solution found: In comment #5 of Ubuntu bug #1626731.

Documented: 02 March 2018.

Alt+space does not open the window operations menu on KDE

The problem: As familiar to Windows users, holding down Alt and pressing the spacebar typically opens up a menu of window operations for the current window, especially useful amongst which are the maximise, minimise and move operations. Some Linux window managers have adopted the same convention, but KDE's default window manager (which I use), KWin, has not. When I upgraded to Fedora 22, my override of the default was lost, and I had forgotten how to override it with Alt+space.

The solution: Open up the KDE "System settings" application. Under the heading "Workspace", click the "Shortcuts" icon. Click "Global Keyboard Shortcuts" in the left pane, then from the drop-down component beside "KDE component" in the main pane, select "KWin". Now in the pane below, scroll down to "Window Operations Menu" and click on the displayed shortcut in the "Global" column. In the box that appears, click "Custom", then click on the button to the right of that displaying the current shortcut and press Alt+space. Finally, click "Apply".

Solution found: Mostly in this StackExchange answer, but the KDE "System settings" layout has changed a little since then, so I had to dig around for myself a bit.

Documented: 23 September 2015.

The CrashPlanDesktop application hangs at its splash screen

The problem: Recently (around August/September 2015) I noticed that when I started the CrashPlanDesktop application on my Fedora Linux desktop, it would hang at its splash screen. This prevented me from adjusting both the backup schedule and the specification of backed up directories and files.

The solution: Run the following command:

sudo chmod go+rx /var/lib/crashplan

Solution found: By checking the CrashPlan log files after discovering in the Sending CrashPlan Log Files To Support article where those log files are located - yes, I was at the point of intending to contact CrashPlan's customer support before I discovered the solution to the problem for myself. Checking /usr/local/crashplan/log/ui_output.log, I found that the application was failing due to being unable to access /var/lib/crashplan/.ui_info due to a permission error. Checking into this, I found that the file itself had the correct permissions, but its parent directory did not. Hence the above command.

First documented: 08 September 2015. Last updated: 23 September 2015.

Left clicking in the scrollbar trough in Firefox moves the scrollbar to the cursor location

The problem: After Firefox was upgraded to version 39.0.3 during my upgrade from Fedora Linux 21 to 22, the behaviour of the scrollbars changed: left clicking in the scrollbar trough now moved the scrollbar to the mouse cursor location rather than, as before, scrolling by one page. The right mouse button now did what the left mouse button used to do. I wanted to revert to the original behaviour.

The solution: Create or edit the file ~/.config/gtk-3.0/settings.ini and add the following:

[Settings]
gtk-primary-button-warps-slider = false

If Firefox is open, then close and reopen it.

Solution found: In the AskUbuntu question, How to fix GTK3 scrollbar behavior.

Documented: 11 August 2015.

A Windows 7 guest installation crashes when booting on a Linux VirtualBox host

The problem: Whilst trying to install from a DVD ISO file a 32 bit version of Windows 7 in a VirtualBox (version 4.3.20_RPMFusion r96996) virtual machine on a 64 bit Fedora Linux 21 host, the installation would boot only up to a certain point - the flying Windows graphics coalescing - and then abort without error message.

The solution: Uncheck the "Enable USB 2.0 (EHCI) Controller" checkbox in the "USB" tab of the virtual machine's settings.

Solution found: By trial and error.

Documented: 15 December 2014.

The tablesorter jQuery plugin stops working when XHTML is delivered with content type application/xhtml+xml

The problem: A short while after I updated this website to use XHTML content negotiation as suggested by the W3C here, I noticed that the tablesorter jQuery plugin that I use on some pages stopped working. Firefox's debugging console displayed the error:

TypeError: thead is undefined

and indicated that it occurred in the file jquery.tablesorter.min.js.

The solution: Convert to lowercase the arguments to all calls (there are only two) to getElementsByTagName() in that file. This is necessary when serving XHTML with its correct content type as explained in the (now-archived) Mozilla Developer Network page, "Writing JavaScript for XHTML".

Solution found: By systematically narrowing down the problem.

Documented: 10 December 2014.

Steam reports an OpenGL GLX direct rendering error under 64 bit Fedora Linux 20 with an NVIDIA video card

The problem: When I ran Steam for the first time on a 64 bit Fedora Linux 20 ASUS laptop with NVIDIA video card and drivers, it reported the following error:

OpenGL GLX context is not using direct rendering, which may cause performance problems.

For more information visit https://support.steampowered.com/kb_article.php?ref=9938-EYZB-7457.

The solution: Install the 32 bit NVIDIA Xorg drivers with the following command:

sudo yum install xorg-x11-drv-nvidia-libs.i686

Solution found: In this post.

Documented: 07 November 2014.

Other sounds are automatically muted during Skype notification events on Fedora Linux 20

The problem: By default, at least on Fedora Linux 20, all other sounds are muted when Skype plays sounds for notifications such as a contact logging in, or a message from a contact. This can be annoying if you're listening to music, because the music will temporarily be muted.

The solution: Comment out (by prepending a hash symbol) the line "load-module module-role-cork" in /etc/pulse/default.pa, and save the changes to this file - you will probably need to do this as root. Reboot. Caveat: this will also prevent Skype from auto-muting sounds during calls, but whilst this is an inconvenience, it is a very minor one - in my case, dealing with it is as simple as pressing the "Pause" multimedia key on my keyboard to pause my music player every time I get an incoming call or want to make an outgoing one.

Solution found: Here.

Documented: 07 November 2014.

Firefox main menu is missing/hidden

The problem: In a recent upgrade (early-mid 2014), the main menu bar in my Firefox browser disappeared. This meant that certain features were no longer accessible to me through the mouse alone, and it was necessary to use the keyboard to gain access to them (by pressing Alt to show the main menu). I wanted the main menu to again be visible constantly, not only when I pressed Alt.

The solution: Right click on the tabs bar in either an empty spot or on the "+" tab, and then left click "Menu Bar".

Solution found: Here.

Discovered: 11 July 2014. Documented: 02 August 2014

GNOME hangs after login

The problem: Normally, I use the KDE desktop, but today I had cause to start up a GNOME desktop session - something I haven't done in a long time, possibly over a year. The session hung immediately after login, from both KDM and GDM - the screen was blank other than wallpaper, and nothing changed visually.

The solution: Change the value of the environment variable LC_ALL from en_AU to en_AU.UTF-8. This might have been a problem only because I use fish rather than the default of bash as my shell. In any case, given that I'm using fish, I had set this variable in the first line of ~/.config/fish/config.fish, originally as:

set -x LC_ALL en_AU

and I changed this to:

set -x LC_ALL en_AU.UTF-8

If you use a different shell (assuming this problem even occurs for other shells), then this variable might be set in a different configuration file. If you use the default Linux shell, bash, then try checking ~/.bashrc, ~/.bash_profile and /etc/bashrc, and look for something like:

export LC_ALL=en_AU

which you will need to change to:

export LC_ALL=en_AU.UTF-8

In "en_AU", the "en" stands for the English language and the "AU" stands for the country Australia. You might have different letters here depending on which language and country you or your system administrator have customised your locale for ("LC" is an abbreviation for "locale"). You can find a list of possible language codes here, and of possible country codes here.

Solution found: By systematically narrowing down the problem.

First documented: 10 June 2014. Last updated: 08 September 2015

Thunderbird displays dates in the format mm/dd/yy instead of dd/mm/yy

The problem: Thunderbird's default format for dates is US style, whereas, as an Australian, I prefer Australian style. I was reminded of the solution to this problem in documenting the above problem.

The solution: Set the environment variable LC_ALL to en_AU.UTF-8 (as noted above, the "en" and "AU" in that setting are language and country codes respectively, for which you can choose variants from the pages linked to in the previous solution). You can do this in the configuration file for your shell. I use fish, so I set LC_ALL in my personal fish config file as described above. If you use the default Linux shell, bash, then you can edit your ~/.bashrc file as described above i.e. by adding the following line:

export LC_ALL=en_AU.UTF-8

For this to take effect, you need to restart Thunderbird in one of the following ways:

• Restart your desktop session - i.e. log out and back in again - and then start Thunderbird.
• First source your shell's config file file on the commandline, and then restart Thunderbird from that same commandline i.e. if your shell is bash, then run the following two commands after closing Thunderbird:

  source ~/.bashrc
  thunderbird

• Manually set the LC_ALL environment variable on the commandline, and then restart Thunderbird from that same commandline i.e. run the following two commands after closing Thunderbird:

  export LC_ALL=en_AU.UTF-8
  thunderbird

Solution found: On the web somewhere; by now I forget exactly where.

First documented: 10 June 2014. Last updated: 02 August 2014