CPU Socket

This is where you’ll find various musings of mine about the world of computing and digital technology. Sometimes, they take the form of personal appraisals but you’ll often find ways of doing things shared on here too. The pace of posting isn’t forced but I do try to share as soon as I find something worthy enough for that. Hope you find something of interest or of use on here.

Changing monitor brightness using the Linux command line

Recently, I felt the need to reduce the brightness of my monitor but did not persuade the hardware buttons to do the job so I started wondering about other means and found that the xrandr command did the trick. The first step was to find out what my display was being called so I executed the following command to retrieve the information using the -q query switch:

xrandr -q | grep " connected"

The output from this looked like this:

DVI-D-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 521mm x 293mm

My device name appeared as the first block of characters in the above so I plugged that into the second command below to achieve the desired adjustment.

xrandr --output DVI-D-0 --brightness 0.9

Any value between 0.0 and 1.0 is acceptable but I went with 0.9 for 90% brightness. The required dimming and brightening then is only a command away.

Updating Flatpack applications on Linux Mint 19

Since upgrading to Linux Mint 19, I have installed some software from Flatpack. The cause for my curiosity was that you could have the latest versions of applications like GIMP or Libreoffice without having to depend on a third-party PPA. Installation is straightforward given the support built into Linux Mint. You just need to download the relevant package from the Flatpack website and running the file through the GUI installer. Because the packages come with extras to ensure cross-compatibility, more disk space is used but there is no added system overhead beyond that from what I have seen. Updating should be as easy as running the following single command too:

flatpack update

However, I needed to do a little extra work before this was possible. The first step was to update the configuration file at ~/.local/share/flatpak/repo/config to add the following lines:

[remote "flathub"]

Once that was completed, I ran the following commands to import the required GPG key:

wget https://flathub.org/repo/flathub.gpg
flatpak --user remote-modify --gpg-import=flathub.gpg flathub

With this complete, I was able to run the update process and update any applications as necessary. After that first run, it has been integrated in to my normal processes by adding the command to the relevant alias definition.

Sorting out sluggish start-up and shutdown times in Linux Mint 19

The Linux Mint team never pushes anyone into upgrading to the latest version of their distribution but curiosity often is strong enough an impulse to make me do just that. When it brings me across some rough edges, then the wisdom of leaving things alone is evident. Nevertheless, doing so also brings its share of learning and that is what I am sharing in this post. It also also me to collect a number of titbits that may be of use to others.

Again, I went with the in-situ upgrade option though the addition of the Timeshift backup tool means that it is less frowned upon than once would have been the case. It worked well too part from slow start-up and shutdown times so I set about track down the causes on the two machines that I have running Linux Mint. As it happens, the cause was different on each machine.

On one PC, it was networking that holding up things. The cause was my specifying a fixed IP address in /etc/network/interfaces instead of using the Network Settings GUI tool. Resetting the configuration file back to its defaults and using the Cinnamon settings interface took away the delays. It was inspecting /var/log/boot.log that highlighted problem so that is worth checking if I ever encounter slow start times again.

As I mentioned earlier, the second PC had a very different problem though it also involved a configuration file. What had happened was that /etc/initramfs-tools/conf.d/resume contained the wrong UUID for my system’s swap drive so I was seeing messages like the following:

W: initramfs-tools configuration sets RESUME=UUID=<specified UUID for swap partition>
W: but no matching swap device is available.
I: The initramfs will attempt to resume from <specified file system location>
I: (UUID=<specified UUID for swap partition>)
I: Set the RESUME variable to override this.

Correcting the file and executing the following command fixed the issue by updating the affected initramfs image for all installed kernels and speeded up PC start-up times:

sudo update-initramfs -u -k all

Though it was not a cause of system sluggishness, I also sorted another message that I kept seeing during kernel updates and removals on both machines. This has been there for a while and causes warning messages about my system locale not being recognised. The problem has been described elsewhere as follows: /usr/share/initramfs-tools/hooks/root_locale is expecting to see individual locale directories in /usr/lib/locale but locale-gen is configured to generate an archive file by default.  Issuing the following command sorted that:

sudo locale-gen --purge --no-archive

Following these, my new Linux Mint 19 installations have stabilised with more speedy start-up and shutdown times. That allows me to look at what is on Flathub to see what applications and if they get updated to the latest version on an ongoing basis. That may be a topic for another entry on here but the applications that I have tried work well so far.

Halting constant disk activity on a WD My Cloud NAS

Recently, I noticed that the disk in my WD My Cloud NAS was active all the time so it reminded me of another time when this happened. Then, I needed to activate the SSH service on the device and log in as root with the password welc0me. That default password was changed before doing anything else. Since the device runs on Debian Linux, that was a simple case of using the passwd command and following the prompts. One word of caution is in order since only root can be used for SSH connections to a WD My Cloud NAS and any other user that you set up will not have these privileges.

The cause of all the activity was two services: wdmcserverd and wdphotodbmergerd. One way to halt their actions is to stop the services using these commands:

/etc/init.d/wdmcserverd stop
/etc/init.d/wdphotodbmergerd stop

The above act only works until the next system restart so these command should make for a more persistent disabling of the culprits:

update-rc.d -f wdmcserverd remove
update-rc.d -f wdphotodbmergerd remove

If all else fails, removing executable privileges from the normally executable files that the services need will work and it is a solution that I have tried with success between system updates:

cd /etc/init.d
chmod 644 wdmcserverd

Between all of these, it should be possible to have you WD My Cloud NAS go into power saving mode as it should though turning off additional services such as DLNA may be what some need to do. Having turned off these already, I only needed to disable the photo thumbnail services that were the cause of my machine’s troubles.

Improving a website contact form

On another website, I have had a contact form but it was missing some functionality. For instance, it stored the input in files on a web server instead of emailing them. That was fixed more easily than expected using the PHP mail function. Even so, it remains useful to survey corresponding documentation on the w3schools website.

The other changes affected the way the form looked to a visitor. There was a reset button and that was removed on finding that such things are out of favour these days. Thinking again, there hardly was any need for it any way.

Newer additions that came with HTML5 had their place too. Including user hints using the placeholder attribute should add some user friendliness although I have avoided experimenting with browser-powered input validation for now. Use of the required attribute has its uses for tell a visitor that they have forgotten something but I need to check how that is handled in CSS more thoroughly before I go with that since there are new :required, :optional, :valid and :invalid pseudoclasses that can be used to help.

It seems that there is much more to learn about setting up forms since I last checked. This is perhaps a hint that a few books need reading as part of catching with how things are done these days. There also is something new to learn.