The device driver for the Canon Pixma TR4540 All-in-one Printer/Scanner does not come bundled with openSUSE, whether you are on Leap or Tumbleweed. It is non available from the official repositories as well, at least I didn't find them, neither on openSUSE Non-OSS or Packman repos.

However, Canon provides the drivers on its website along with an installation script. The tarball containing the the .rpm files and the script can be from its package-archive. At the time that I tested, the driver package was at version 5.70.

Extract the files.

tar xzvf cnijfilter2-5.70-1-rpm.tar.gz

Then, change in to the cnijfilter2-5.70-1-rpm directory and run the installation script as the root user.

cd cnijfilter2-5.70-1-rpm && sudo ./install

Finally, follow the on-screen (CLI) instructions to complete the setup.

That's it! Your Canon Pixma TR4540 setup should be complete & ready to use.

Dear Tumbleweed users and hackers,

This week has shown that Tumbleweed is indeed back at full speed. We have published new snapshots daily. Of course, that also means we could rely on not receiving broken things that managed to slip through stagings without being noticed. So thanks go mostly to the developers/maintainers who submitted pre-tested things. And openQA of course!
The snapshots were numbered 0826…0901.

The most notable changes during this week included:

• The missing pieces of the GNOME 40.4 update (complete now)
• rpmlint 2.1
• openssl 1.1.1l
• pipewire 0.3.34
• Linux kernel 5.13.13

The staging projects are currently filled with those major changes:

• Mesa 21.2.1
• Mozilla Firefox 91.0.2
• systemd 249.4
• Linux kernel 5.14.0
• KDE Plasma 5.22.5
• KDE Applications 21.08.1
• glibc 2.34: bug tracking remaining failures: boo#1189079
• shadow 4.9: boo#1190145 and boo#1190146

Snapshot releases of openSUSE’s rolling release Tumbleweed have been constantly trickling out to users since last week’s review.

This review will cover the five snapshots made available since August 26. Each of the snapshots delivered about a handful of updated software packages.

Snapshot 20210831 updated bind to version 9.16.20, which fixed a Common Vulnerability and Exposure; CVE-2021-25218 an assertion failure could have allowed an attacker to abused the Path Maximum Transmission Unit Discovery protocol to trick bind into exceeding the interface MTU. The C Library for manipulating module metadata files libmodulemd updated to 2.13.0 and the modulemd-validator enables a user to constrain a document type with a new --type option. The other packages to update in the snapshot were libqmi 1.28.8 and libjpeg-turbo 2.1.1, which fixed a couple regressions affecting AArch64 and arm 32-bit hardware.

Linux Kernel 5.13.13 was one of the two packages updated in the 20210830 snapshot. The Direct Rendering Manager had some fixes in the kernel update and added an AAL output size configuration. The kernel update also had an Advanced Linux Sound Architecture enablement for the 4-speaker output in the Dell XPS 15 9510 laptop. The other package to update in the snapshot was perl-Image-ExifTool, which had a version bump to 12.30.

Two CVEs were addressed in the update of OpenSSL to version 1.1.1l in snapshot 20210828; one of the CVEs fixed an SM2 Decryption Buffer Overflow that could have allowed for the possibility of changing an application’s behaviour or causing an application to crash. Internal latency of ALSA devices can now be configured with the new PipeWire 0.3.34 version and Tumbleweed enabled the usage of libcamera in the audio and video package to allow for some experimental support. Network protocol analyzer Wireshark 3.4.8 provided a handful of fixes; one of the fixes addressed a dissector bug when processing a Bluetooth Handle Value Notification. Other packages updated in the snapshot were libgcrypt 1.9.4, libssh 0.9.6, pkgconf 1.8.0, python-aioitertools 0.8.0 and yast2-installation 4.4.17, which killed a lot of YCP zombies; YCP is the language YaST was originally written in before moving to Ruby.

Sound artists and musicians can use an updated Audacity that came in snapshot 20210827. The 3.0.4 version of Audacity fixed a compatibility issue with GNU Compiler Collection 11; it also provided some crash fixes affected by the use of multiplied envelope points when using Filter Curve EQ or Graphic EQ. A version bump was made to gnome-desktop 40.4. Eight months worth of mobile-broadband-provider-info updates were in the snapshot and the 20210805 version improved services providers in Europe, Africa and the Americas. Other packages to update in the snapshot were three RubyGems packages, ncurses 6.2.20210814 and publicsuffix 20210823.

Snapshot 20210826 wasn’t covered in the last Tumbleweed blog. The snapshot updated libopenmpt 0.5.11, package management library libzypp 17.28.1, USB network protocol usbredir 0.11.0, the file system debugging tool xfsprogs 5.13.0 and yast2-add-on 4.4.1.

"Themes in GNOME" is a complicated topic in technical and social terms. Technically there are a lot of incomplete moving parts; socially there is a lot of missing documentation to be written, a lot of miscommunication and mismatched expectations.

The following is a brief and incomplete, but hopefully encouraging, summary of the status of themes in GNOME. I want to give you an overall picture of the status of things, and more importantly, an idea of how you can help. This is not a problem that can be solved by a small team of platform developers.

I wish to thank Alexander Mikhaylenko for providing most of the knowledge in this post.

Frame of reference

First, I urge you to read Cassidy James Blaede's comprehensive "The Need for a FreeDesktop Dark Style Preference". That gives an excellent, well-researched introduction to the "dark style" problem, the status quo on other platforms, and exploratory plans for GNOME and Elementary from 2019.

Go ahead, read it. It's very good.

There is also a GUADEC talk about Cassidy's research if you prefer to watch a video.

Two key take-aways from this: First, about this being a preference, not a system-enforced setting:

I’m explicitly using the language “Dark Style Preference” for a reason! As you’ll read further on, it’s important that this is treated as a user “preference,” not an explicit “mode” or strictly-enforced “setting.” It’s also not a “theme” in the sense that it just swaps out some assets, but is a way for the OS to support a user expressing a preference, and apps to respond to that preference.

Second, about the accessibility implications:

Clearly there’s an accessibility and usability angle here. And as with other accessibility efforts, it’s important to not relegate a dark style preference to a buried “Universal Access” or “Accessibility” feature, as that makes it less discoverable, less tested, and less likely to be used by folks who could greatly benefit, but don’t consider themselves “disabled.”

Libadwaita and the rest of the ecosystem

Read the libadwaita roadmap; it is very short, but links to very interesting issues on gitlab.

For example, this merge request is for an API to query the dark style and high-contrast preferences. It has links to pending work in other parts of the platform: libhandy, gsettings schemas, portals so that containerized applications can query those preferences.

As far as I understand it, applications that just use GTK3 or libhandy can opt in to supporting the dark style preference — it is opt-in because doing that unconditionally in GTK/libhandy right now would break existing applications.. If your app uses libadwaita, it is assumed that you have opted into supporting that preference, since libadwaita's widgets already make that assumption, and it is not API-stable yet — so it can make that assumption from the beginning.

There is discussion of the accessibility implications in the design mockups.

CSS parity across implementations

In GNOME we have three implementations of CSS:

• librsvg uses servo's engine for CSS selector matching, and micro-parsers for CSS values based on servo's cssparser.

• GTK has its own CSS parser and processor.

• Gnome-shell uses an embedded version of libcroco for parsing, but it does most of the selector matching and cascading with gnome-shell's own Shell Toolkit code.

None of those implementations supports @media queries nor custom properties with var(). That is, unlike in the web platform, GNOME applications cannot have this in their CSS:

@media (prefers-color-scheme: dark) {
  /* styles for dark style */
}

@media (prefers-color-scheme: light) {
  /* styles for light style */
}

Or even declaring colors in a civilized fashion:

:root {
  --main-bg-color: pink;
}

some_widget {
  background-color: var(--main-bg-color);
}

Or combining the two:

@media (prefers-color-scheme: dark) {
  :root {
    --main-bg-color: /* some nice dark background color */;
    --main-fg-color: /* a contrasty light foreground */;
  }
}

@media (prefers-color-scheme: light) {
  :root {
    --main-bg-color: /* some nice light background color */;
    --main-fg-color: /* a contrasty dark foreground */;
  }
}

some_widget {
  background-color: var(--main-bg-color);
}

Boom. I think this would remove some workarounds we have right now:

• Just like GTK, libadwaita generates four variants of the system's stylesheet using scss (regular, dark, high-contrast, high-contrast-dark). This would be obviated with @media queries for prefers-color-scheme, prefers-contrast, inverted-colors as in the web platform.

• GTK has a custom @define-color keyword, but neither gnome-shell nor librsvg support that. This would be obviated with CSS custom properties - the var() mechanism. (I don't know if some "environmental" stuff would be better done as env(), but none of the three implementations support that, either.)

Accent colors

They are currently implemented with GTK's @define-color, which is not ideal if the colors have to trickle down from GTK to SVG icons, since librsvg doesn't do @define-color - it would rather have var() instead.

Of course, gnome-shell's libcroco doesn't do @define-color either.

Look for @accent_color, @accent_bg_color, @warning_color, etc. in the default stylesheet, or better yet, write documentation!

The default style:

Accent color set to orange (e.g. tweak it in GTK's CSS inspector):

/* Standalone, e.g. the "Page 1" label */
@define-color accent_color @orange_5;

/* background+text pair */
@define-color accent_bg_color @orange_4;
@define-color accent_fg_color white;

Custom widgets

Again, your app's custom stylesheet for its custom widgets can use the colors defined through @define-color from the system's stylesheet.

Recoloring styles

You will be able to do this after it gets merged into the main branch, e.g. recolor everything to sepia:

@define-color headerbar_bg_color #eedcbf;
@define-color headerbar_fg_color #483a22;

@define-color bg_color #f9f3e9;
@define-color fg_color #483a22;

@define-color dark_fill_color shade(#f9f3e9, .95);

@define-color accent_bg_color @orange_4;
@define-color accent_color @orange_5;

Of course shade() is not web-platform CSS, either. We could keep it, or redo it by implementing calc() function for color values.

Recoloring icons

Currently GTK takes some defined colors and creates a chunk of CSS to inject into SVG for icons. This has some problems.

There is also some discussion about standardizing recolorable icons across desktop environments.

How you can help

Implement support for @media queries in our three CSS implementations (librsvg, gnome-shell, GTK). Decide how CSS media features like prefers-color-scheme, prefers-contrast, inverted-colors should interact with the GNOME's themes and accessibility, and decide if we should use them for familiarity with the web platform, or if we need media features with different names.

Implement support for CSS custom properties - var() in our three CSS implementations. Decide if we should replace the current @define-color with that (note that @define-color is only in GTK, but not in librsvg or gnome-shell).

See the libadwaita roadmap and help out!

Port applications to use the proposed APIs for querying the dark style preference. There are a bunch of hacky ways of doing it right now; they need to be migrated to the new system.

Personally I would love help with finishing to port gnome-shell's styles to Rust - this is part of unifying librsvg's and gnome-shell's CSS machinery.

Collecting process accounting logs on Linux with syslog-ng

Process accounting logs are collected into binary log files on Linux. You can turn them into human readable format locally, using various tools. You can also use syslog-ng to read those files.

Lean how syslog-ng can parse those binary logs, create name-value pairs from them and store the results from my latest blog: https://www.syslog-ng.com/community/b/blog/posts/collecting-process-accounting-logs-on-linux-with-syslog-ng

Most people only know that I work in IT. Some even call me a hacker – which I really appreciate :-) However, by university degree I am an environmental engineer (and English - Hungarian translator). Even if I never worked in my field, except for some student jobs, I still follow any news related to the environment closely. This is why I was very happy to learn, that my home city, Budapest, introduced bee pastures in the city.

Bee pastures

So, what are bee pastures? Most people expect that public areas in a city have shortly cut grass. It is convenient for humans, you can walk on it, you can play games on it or bask in the sun. The price is that it needs to be cut regularly and there are no flowers: bees cannot eat there. Bees have an essential role in our ecosystems. Unfortunately, the area where they eat and live is continuously shrinking, due to humans. Establishing bee pastures, areas with the right mix of flowering plants can help the bee population to survive and grow. Establishing bee pastures in selected areas of cities can help in multiple ways. It helps the bees, it looks nice and can also save costs on lawn mowing.

Where it went wrong in Budapest

Turning a grass area into bee pasture does not mean that it does not need maintenance any more. It just means less frequent maintenance. Of course, there are also some properly maintained bee pastures in Budapest. The problem is, that in most cases, in practice it means an area with a “Bee Pasture” sign and completely left alone. In real life I have only seen this problematic version, where behind the “Bee Pasture” sign one could only see overgrown areas, full of highly allergenic plants.

My Facebook post

Facebook is aware, that I like reading about environmental issues. So, one of the posts on my time line was a photo from the UK, which showed bee pastures on the streets and parks of a small town. It looked like what you would expect when someone mentions bee pasture. I shared the photo with a short text: “This is a fantastic idea, and there are places where they do this properly”.

Offending two sides

So, where is the problem? If you read so far, you can see that I support a progressive idea and criticize how it is carried out. The discussion below my post grew into a flame-war. To understand why, here is some background information. The “bee pasture” idea came from the leaders of the city of Budapest, led by a major opposition figure. What does it mean? Anyone supporting the opposition parties support bee pastures, even if in practice it means large fields of allergenic plants. Anyone supporting the governing party considers the bee pasture idea crazy, even where it is implemented properly. My post offended both sides, as I supported an opposition idea, but I criticized how it was implemented.

This post was only shared with my Facebook friends. Still, after a few days my post was reported enough times to be deleted.

How does it come to an IT blog?

You might wonder how this story is related to IT, the primary focus of my blog. It is related. Most of the time I am independent. There are hot debates in IT as well, where I avoid taking a side – at least publicly. If I need to write about the topic publicly for example to inform syslog-ng users in a question, I keep a safe distance from all sides involved. I do not judge who is good, who is bad, just focus on how the given problem affects syslog-ng users. Just to mention a few:

• ElasticSearch vs. OpenSearch – the most frequently used log destination in syslog-ng
• RHEL vs. CentOS Stream vs. CentOS replacements – the most frequently used operating system to run syslog-ng

Taking a side, seeing everything in black and white is easier: less thinking, feeling of belonging. But that’s not how I work in IT or in real life.

You can also make a difference if you have a garden. Make sure that you have some flowering plants in parts of your garden all around the year. And avoid using chemicals as much as possible.

For some people, vacation season is just the right time for housekeeping or for learning new skills. And that’s exactly what the YaST team has been doing in the latest two sprints.

• We improved some YaST internals including:
  • Management of the Help button in text mode
  • Unmounting of file-systems at the end of installation
  • Handling of progress bars
• Our users also made YaST better with their contributions
• The dedicated subset of the YaST Team keeps making progress regarding the Release Tools

Let’s go into the details.

Keeping the YaST Internals in Shape

In the software development world is not uncommon to sweep the dirt under the carpet. If something seems to work from the user point of view, just leave it as it is. But there is no carpet to hide anything when you develop Free Software with an open spirit. And in the YaST Team we simply don’t feel comfortable when we know the pieces under the hood are not really well adjusted. Thus, we invested some of our summer time fixing some internal issues (both real and potential), although none of them currently have visible impact of our users.

• All YaST screens contain a Help button that shows an explanatory text. But, what happens if there is no such text? It’s a theoretical problem (there is ALWAYS a help text) but the situation in the ncurses text mode really needed a better handling.
• Unmounting file-systems at the end of the installation process is another of those things that seem to work flawlessly… until you take a look to the YaST logs and find out it used to be an slightly convulted process. But we restructured the component taking care of the process and things now look equally good in the surface and under the hood.
• The way progress bars are handled in YaST is admitedly error-prone and could result in the user interface crashing in some extreme situations. We also improved that by making the Yast::Progress internal module more robust.

Integrating Community Contributions

Another of the great things of working in an Open Source project is getting contributions from your own users. In that regard, we recently added support for the AFNOR variant of the French keyboard, which was useful to realize we haven’t incorporated such layout to SUSE Linux Enterprise. We did now, so both SLE and openSUSE got better thanks to the openSUSE community. Something that will soon happen also to the YaST Journal module as soon as we merge this other contribution currently under review.

Release Tools: We Keep Learning

And talking about collaboration, in our previous post we told you about our new mission of helping with the development and maintenance of the (open)SUSE Release Tools. We keep working on that front, although progress can only be slow when most of the people we have to interact with (and a big part of the YaST Team itself) is on vacation. Nevertheless, we keep researching possible solutions for the known problems, improving the testing infrastructure and using a test-driven approach to lower the entry barrier for newcomers.

See you soon

The vacation season in Europe is comming to an end, so we hope to have more exciting news for upcoming blog posts. Meanwhile, please keep helping us and having a lot of fun!