Author Archives: Lorenzo Bettini

About Lorenzo Bettini

Lorenzo Bettini is an Associate Professor in Computer Science at the Dipartimento di Statistica, Informatica, Applicazioni "Giuseppe Parenti", Università di Firenze, Italy. Previously, he was a researcher in Computer Science at Dipartimento di Informatica, Università di Torino, Italy. He has a Masters Degree summa cum laude in Computer Science (Università di Firenze) and a PhD in "Logics and Theoretical Computer Science" (Università di Siena). His research interests cover design, theory, and the implementation of statically typed programming languages and Domain Specific Languages. He is also the author of about 90 research papers published in international conferences and international journals.

Installing Arch Linux with the archinstall script

After using EndeavourOS for a while, I also decided to try Arch itself!

I did not feel ready to go through the manual procedure (but I’ll do that someday), and I heard about the archinstall script, which comes in the Arch official ISO. After watching a few videos and reading a few blog posts, I tried that myself, first on a VM and then on a real machine.

I can anticipate that I liked this installation procedure. Still, it is not perfectly usable in a multi-boot environment, as I’ll say near the end of this post, where I summarize my experience with the installation.

In this post, I’ll first show an installation on a VM (and I suggest you try that one), then briefly describe the installation on a real machine.

If you want to try that, you have to download an official Arch ISO. Once you booted into the live ISO, you must connect to the Internet as described in the official documentation.

Now, it’s time to run the installer:

And you have access to the main installation menu:

You see, it’s easy to use, especially if you’re familiar with other Linux installation programs.

The first three entries are easy to deal with.

The fourth, “Select harddrives,” requires some care because it’s where you deal with your disk! You have to select the correct drive. In my case:

Since I’m on a VM, I’ll simply choose to wipe everything on that drive and let the installer handle the partitioning automatically. That’s easy in a VM, and that’s what I’ve seen in all demos on the web (but, as I’ll show later, things are more complicated in a multi-boot environment):

Then, you choose the filesystem EXT4, BTRFS, etc.

For the bootloader, I chose GRUB, which is the one I’ve always used.

Concerning the user accounts, it’s best NOT to set a root password: it’s better to create a user with administrator rights (so that you later rely on the good ol’ “sudo”). An interesting feature of this installation procedure is that it lets you create as many users as possible. On the contrary, typically, other Linux installations only allow you to create a single user.

The other interesting menu entry is the one to choose the profile. I’m choosing “desktop”:

And in particular, I’m choosing GNOME (you see that you have plenty of choices):

Moreover, you can select the graphic drivers:

And the kernels:

Since, for the moment, you could just select from a predefined set of choices, you are given a chance to manually specify additional packages to install (but you have to know them by their name). In this example, I’m installing “firefox”:

It’s also crucial to configure the network for the installed system. If you use GNOME or KDE, I’d say that it’s best to choose “NetworkManager”:

Once you’ve done with all the menu entries, before starting the actual installation, you’re given a chance to save these configurations, which is helpful if you want to use the same configurations on other machines or to do some further customizations:

Now, it’s time to choose “Install”; a countdown starts to abort the installation in case you just remembered you’ve done something wrong:

The installation starts and in a few minutes (where a few packages will be downloaded)…

…you should get to the end of the installation, where, if you want, you can also tweak the installed system before rebooting:

If you choose “no”, you’re back to the live environment:

And you can now reboot to (hopefully) enjoy your installation:

Having installed GNOME, I’m presented with a few options, and I choose the first one, that is, GNOME on Wayland:

You see that the GNOME installation is a vanilla one.

OK, that was a VM, and it was straightforward to install Arch with the installation script. It’s also easy if you plan to install ONLY Arch on your computer (by wiping all the rest).

Things are not working completely fine if you want to install it on a computer with other Linux installations, which you want to keep and be able to boot into. In this case, of course, you cannot wipe the selected hard drive and must do manual partitioning. The installation script is still helpful in that respect (I’m not showing anything in this blog post), but you must be aware of a small problem.

In fact, due to an issue, which, at the time of writing, is still open, specifying to mount an existing EFI partition into “/boot/efi“, which, as far as I know, it’s the standard mount point in most distributions (every distribution I know at least). You must specify a mount point “/boot” and that must be a boot partition (with the boot flag). Of course, that’s what I’ve done myself; I specified the exiting EFI partition (the first partition of the installation drive in my computer) for the mount point “/boot”. However, the installer will treat that directory as if it was /boot/efi in other installations. Thus, it will copy the booting files directly there. As a sad result, the Arch installation will not be detected when rebooted. You will only see an existing installation’s GRUB menu (and running os-prober from an existing installation does not seem to help). Thus, you end up with the Arch installation that you cannot boot.

The only solution I found to boot into the Arch system was to apply the mechanisms shown in my other post and configure the Fedora GRUB with an entry pointing directly to the EFI partition, i.e., according to the post mentioned above, something like the following (remember, on my computer the EFI partition is the first one, and I installed Arch on the partition 13):

Or even like that (i.e., without specifying the root partition of the Arch installation at all and just relying on the grub that the installer created directly on the EFI partition):

Besides this problem, the installation script archinstall is really interesting and still under development.

Locate and BTRFS

I’ve always been using the locate command (provided by the mlocate package or by the new plocate package), which quickly searches for files and directories by their names. The command relies on the database built by the command updatedb (which should be run periodically, e.g., by enabling the plocate-updatedb.timer service for plocate).

Unfortunately, by default, it does go well with the BTRFS filesystem and its subvolumes (see, e.g., this bug), resulting in empty results for all searches basically.

Fortunately, the solution is quite simple:

  1. edit the file /etc/updatedb.conf
  2. replace PRUNE_BIND_MOUNTS = “yes” with PRUNE_BIND_MOUNTS = “no”
  3. save, exit and re-run updatedb

Then, you can enjoy locate’s search results 🙂

Linux EndeavourOS Artemis Review

I have already blogged about EndeavourOS, which I use most of the time on a few laptops. Since EndeavourOS, based on Arch, is a rolling release, I update it almost daily and don’t need to install it from scratch when a new release comes out, like Artemis, which was released a few days ago. However, since I wanted to switch from the EXT4 file system to BTRFS (since I started to experiment with this file system and its snapshot capabilities), I took the chance to try this new release by installing it from scratch (of course, using BTRFS this time).

I’ll first go through the installation, but I can anticipate that, once again, I’m impressed by EndeavourOS. This installation feels really fast, maybe due to BTRFS or the new kernel (instead of the LTS kernel, I now use the latest one provided by the distribution) or both. Most of all, EndeavourOS is pure Arch but with outstanding defaults. Indeed, the KDE and GNOME environments are vanilla ones.

Installation

As usual, the first thing to do, once booted in the live environment, which in this case is XFCE, is set up the network connection. You might also want to change the keyboard layout (Disable system defaults and install your layout, in my case, it’s the Italian layout):

Then, let’s update the mirrors (typically by selecting your state) and start the installer.

I choose the “Online” method because I want to install KDE Plasma instead of Xfce.

You have to wait a few seconds (or about a minute) for the installer to download the modules (I always prefer to install any operating systems in English):

Maybe, due to a bug, the location has been found successfully, but the English version proposed is not the right one, so I have to change it to Americ English again:

After setting the keyboard layout (this time for the installed system), it’s time for partitioning.

Since on this computer I have a few Linux installations, including the old version of EndeavourOS I’m going to replace, I choose Manual partitioning (and not “Replace a partition” because that would keep the same file system type, EXT4, while I want to switch to BTRFS).

I Edit the partition, select “Format” (otherwise, I cannot change the File system type), modify the File system (BTRFS), and specify the mount point.

Before going on, we must specify to mount the EFI partition (into /boot/efi) without formatting it and ensure the “boot” flag is selected. This way, the installer can properly install GRUB.

WARNING: on another computer, the installer complained that I did not select a boot partition with at least 300Mb (mine was just 200Mb). Since I knew there was enough space in that partition, I ignored the warning, and the installation went fine.

As for the desktop, I select Plasma.

And then, we can select the single packages. Note that, different from my previous review, you choose the packages after selecting the desktop, so that a few packages, in particular, the ones of the chosen desktop, have already been selected:

In this blog post, I’m not going to install GNOME besides KDE, but I also select the “Printing-Support” and the “Support for HP Printer/Scanner” checkboxes.

As usual, then you have to specify your user’s details, and then it’s time to take a look at the summary:

Let’s start the installation. It might take a few minutes because it’s an “Online” installation, so it has to download several packages.

You can press “Toggle log” during the installation to see the installer’s log.

When it’s done, it’s time to restart the computer.

First impressions

As in the previous blog post, I must note that the Discover icon is still in the taskbar, though the software manager Discover is not installed at all.

Maybe because I selected KDE Plasma only, the Wayland session has not been installed, while in my previous post, I installed both GNOME and KDE. However, I just had to run this command:

And then I could enjoy Plasma also in Wayland, which seems to be pretty usable.

A nice addition is a firewall applet in the taskbar

Here’s neofetch:

Printing support is excellent! I connected an old USB HP Deskjet printer, and I got these notifications from Plasma:

The printer has been automatically installed correctly (I only had to configure a few things like paper size and color mode).

Setting up my Google accounts (drive access and calendar) is as cumbersome as always, but I did not experience any problems once I finished.

Power consumption on the battery is also excellent, but that was true in the past, so nothing changed in that respect.

All in all, this distribution keeps on being awesome.

As I initially anticipated, you have Arch and its vanilla desktop environments, but with useful and reasonable defaults. Moreover, the installation is effortless! 🙂

Enabling Hibernation in Arch-based distros

I had already posted about enabling hibernation in Linux, particularly in Ubuntu.

Thanks to the script hibernator, the procedure is much more straightforward in Arch-based distros (including Manjaro and EndeavourOS).

First of all, make sure you first install the package update-grub.

The package hibernator is available from AUR, but currently, there’s a problem with the build instructions. Thus, we must install it manually. There’s no need to install the script anywhere: it’s just a matter of cloning the script from GitHub and running it once:

Then, before running the script (as a superuser), we must decide where we want the suspend-to-disk to take place: either in a swap partition or in a swap file (please keep in mind that currently, the script cannot handle hibernation into a swap file of a BTRFS partition).

If we want a swap file, the script can create that for us, and we can also specify the size of the swap file. Here’s the quote from the home page of the project

Hibernator accepts desired size of swapfile as arguments. Running hibernator 2G creates 2 Gb swapfil, hibernator 1000M creates 1000 Mb swapfile. The script defaults to 4G if no arguments are given.

If we want a swap partition, we must ensure the partition is already in place and that our /etc/fstab already refers to that (i.e., it mounts it appropriately).

When we’re ready, we just run the script with sudo. The script will update the GRUB command line with the resume option and a resume hook to /etc/mkinitcpio.conf. Finally, it will update the GRUB configuration (with update-grub, that is why you need to install this package beforehand).

Here’s an example of the output:

And that’s all: we just reboot, and hibernation is ready to be used!

Before rebooting, you might want to check that the GRUB_CMDLINE_LINUX_DEFAULT variable in /etc/default/grub has been set with a valid resume entry (if you rely on a swap partition, which has been properly specified in /etc/fstab, it should contain a reference to the UUID of the swap partition):

You can test that, as usual, with

You may also want to refer to the older post enabling hibernation in Linux, particularly in Ubuntu, for other mechanisms related to hibernation, like suspend and then hibernate.

Timeshift and grub-btrfs in Linux Arch

After looking at the very nice videos of Stephen’s Tech Talks, in particular, this one https://www.youtube.com/watch?v=6wUtRkEWBwE, I decided to try to set up Timeshift, Timeshift-autosnap, and grub-btrfs in my Linux Arch installation, where I’m using BTRFS as the filesystem. These three packages allow you to have a timeshift snapshot automatically created each time you update your system; moreover, a new grub entry is automatically generated to boot into a specific snapshot.

The video mentioned above is handy, but unfortunately, some recent changes in Timeshift itself broke the behavior of the two other packages. In this post, I’ll try to show how to fix the problem and go back to a working behavior. I’ll also show an experiment using the snapshots so that, hopefully, it’s clear what’s going on in the presence of such snapshots and how to use them in case you want to revert your system.

First of all, let’s install timeshift and timeshift-autosnap (the latter depends on the former, and they are both available from AUR; I’m using the AUR helper yay here):

The first problem is that timeshift has recently changed the strategy for creating snapshots. Instead of creating them in /run/timeshift/backup/timeshift-btrfs/snapshots, it now creates them in /run/timeshift/<PID>/backup/timeshift-btrfs/snapshots, where <PID> is the PID of the Timeshift process. Each time you run Timeshift, the directory will be different, breaking grub-btrfs (which expects to find the snapshots always in the same directory).

Fortunately, there’s a workaround: we add an entry to /etc/fstab in order to mount explicitly the path /run/timeshift/backup/timeshift-btrfs/snapshots:

where, of course, <UUID> has to be replaced with the same UUID of the physical disk partition.

Reboot, and then Timeshift will also put the snapshot in that directory (besides the one with the PID, as mentioned above). You can try to create a snapshot to verify that (this also allows us to use the Timeshift wizard so that we specify to create BTRFS snapshots).

Let’s make sure the mount point is active (and note the unit name)

Let’s now install grub-btrfs

We need to configure that to monitor the Timeshift snapshot directory instead of the default one (/.snapshots).

The file contents

should be replaced with

Let’s reload and re-enable the monitoring service:

If we have already created a few snapshots, we can run update-grub (or, if you have not installed the package update-grub, use the command “grub-mkconfig -o /boot/grub/grub.cfg”) and verify that new grub entries are created for the found snapshots:

We can also restart the system and prove that we can access the GRUB submenu with the generated entries for the snapshots.

IMPORTANT: If you have several Linux distributions on your computer and you use a multiboot system like the one I blogged about, and this distribution is not the main one, you will have to manually tweak the entry in your main distribution’s GRUB menu. See the linked blog post near the end.

Some experiments

Let’s do some experiments with this configuration.

Here’s the kernel I’m currently running:

I’m updating the system (I’m skipping some output below, and you can ignore the “stale mount” errors):

So it created a snapshot before updating the system (in particular, it installed a new kernel version). Let’s reboot and verify we are running the new kernel (5.18.8 instead of 5.18.7):

Let’s reboot and select from GRUB the latest snapshot (remember, the one before applying the upgrade), so timeshift-btrfs/snapshots/2022-07-02_15-35-53 (snapshots are presented in the grub submenu from the most recent to the oldest one). We do that by pretending that the update broke the system (it’s not the case), and we want to get back to a working system before the update we have just performed.

You see that the “Authentication Required” dialog greets us, and in the background, you can see the notification that we “booted into Timeshift Snapshot, please restore the snapshot”:

The password is required because it’s trying to run Timeshift:

In the screenshot, you can see that we are now using the older kernel since we booted in that snapshot where the update has not yet been performed. We have to restore the snapshot manually; otherwise, on the next boot, we’ll get back to the updated system version and not in the snapshot anymore.

So, let’s restore the snapshot:

You see, Timeshift has just created another snapshot ([LIVE]). We now reboot normally (that is, using the main grub entry, NOT the snapshot entries).

Once rebooted normally, we can verify again that we are running the old kernel:

Let’s have a look at Timeshift, and we can see the last snapshot is an effective one, not a LIVE one:

Yes, we are now in a system where the update above has never been applied.

Let’s try to rerun the update command (we don’t effectively execute the update, it’s just an experiment):

Why? Because the snapshot had been created automatically by timeshift-autosnap before applying the updates while the package manager was running, its lock is still there.

Let’s remove the lock and try to rerun the update:

The output is similar to the one shown above (unless there are even more new updates in the meantime, which might happen in a rolling release), but something is missing:

Why? Because the downloaded packages in the cache are NOT part of the saved snapshot, they are still present in the current system, even though we restored the snapshot. Why are the cached packages still there, but the lock has been restored with the snapshot? That’s due to the way subvolumes are specified in the /etc/fstab:

You see, the cache of downloaded packages and the logs are NOT part of the snapshots, while /var/lib (including the pacman lock) is part of the snapshots.

Let’s now revert the snapshot: we select the one with “Before restoring…”.

Again, we are now in a LIVE situation, and Timeshift tells us again to reboot to make it effective.

Let’s reboot (normally, by using the main grub entry).

We’re back to the updated system, and there’s nothing to update (again, unless new updates have been made available in the meantime):

If we’re happy with the updated system, we can also remove those two snapshots (remember that grub-btrfs monitors the snapshots so that it will update its grub submenu entries):

I hope you find this blog post helpful, and I hope it complements the wonderful video of Stephen’s Tech Talks mentioned above.

KDE Plasma 5.25 in Arch

After the recent release of KDE Plasma 5.25, this version landed a few days ago in Arch-based distros like EndeavourOS (the one I’m writing from).

Although I’m mostly a GNOME user, I also have a few distributions installed where I’m using KDE Plasma.

The new features that impressed me most are related to eye candies 🙂

First, the “Present Windows” effect now looks the same as the new “Overview” effect. If we compare the “Present Windows” effect in the previous version (5.24):

with the new one:

we can see a significant improvement: in the earlier versions, the windows not selected were too dark, making it hard to distinguish them. This behavior relates to an old bug (10 years old): https://bugs.kde.org/show_bug.cgi?id=303438. This bug has been fixed by rewriting this effect “to use the same modern, maintainable backend technology found in the Overview effect.”

I use this effect a lot (I also configured the “Super” key to use this effect, simulating what happens in Gnome for its “Activities” view), and I use the filter to filter the open windows quickly. So I appreciate this usability change a lot!

One detail I do not like in this new version of “Present Windows” is that the filter textbox remembers the entered text. Thus, the next time you use it, the presented windows are already filtered according to the previously entered text. I’m not sure I like this.

The other cool thing introduced is the automatic accent color! Accent colors were introduced a few versions ago in Plasma, but now you can have Plasma automatically adjust the accent color from the current wallpaper:

If you use a wallpaper changer mechanism (like the one provided by Plasma), possibly by downloading new wallpapers (like Variety), you will get nice accent colors during the day. Here are a few examples produced running Variety to change the wallpaper:

Maybe it’s not an important feature, but, as we say in Italy, “Anche l’occhio vuole la sua parte” 😉

The last new feature that positively impressed me is that now KRunner also shows Java files (and probably other programming languages related files) when you search a string. Previously, although “Baloo” (the file indexing and file search framework for KDE) knew about these files, KRunner was only showing .txt files and a few others, but not Java files.

Concerning Wayland, one thing I noted is that if I start a Plasma Wayland session using a brand new user, it automatically scales the display in case of an HDPI screen. Wayland usability in Plasma has not improved since my last experiments (see KDE Plasma and Wayland: usability).

 

Xtext 2.27.0: update your Xbase compiler tests

If you update to Xtext 2.27.0 and have compiler tests for your Xbase DSL that assert the output of the compilation, you’ll get lots of failures after the update.

I am guilty of that 😉
Well, for a good reason, at least 🙂

In fact, I worked on this issue: https://github.com/eclipse/xtext-extras/issues/772 and its fix is included in Xtext 2.27.0.

Now, the Xbase compilation mechanism does not generate useless empty lines anymore (before, it added lines with two spaces). Your compiler tests will fail because the output is different.

I personally fixed my tests in my DSLs by simply using the Find/Replace mechanism of Eclipse with this substitution pattern (there are two space characters between the tab character and the newline character):

If you have deep nesting in your compilation output, you might have to repeat this substitution with more than two characters, but this should not be required unless you generate nested classes or something like that.

With the above substitution a test like the following one:

will become like the following one (you see the difference: no empty line with two characters between the two generated constructors:

Now your tests should be fixed 🙂

Configure Arch Pacman

Pacman is the package manager in Linux Arch and Linux Arch-based distributions.

I’ve been using EndeavourOS for some time, and I enjoy it. EndeavourOS is pretty close to vanilla Arch. I also experimented with pure Arch (more on that in future blog posts). However, the output of pacman in EndeavourOS is much more excellent and “eye candy” than in Arch. However, it’s just a matter of configuring /etc/pacman.conf a bit in Arch to have the “eye candy” output.

These are the options to enable in the [options] section in that file (the ParallelDownloads does not have to with the output, but it’s a nice optimization):

Without these options, this is the output of pacman (e.g., during an upgrade):

And this is the output with the options above enabled:

Besides the colors, you can spot c’s for the progress representing “Pacman,” the video-game character, eating candies (that’s the aim of the option ILoveCandy)… waka waka waka!  🙂

The colors are also helpful when searching for packages:

Happy Pacman! 🙂

macOS: switch between different windows of the same application

Maybe this is well-known to macOS users, but it wasn’t clear to me as a Linux user.

As a Linux user, I’m used to using Alt+Tab to switch between different windows. But I also use the shortcut to switch between different windows of the same application. In Gnome, the shortcut is Alt+<the key above Tab>, which is cool because it works with any keyboard layout. In KDE it is Alt+backtick (`), which has to be changed in Italian keyboards, like mine to Alt+\. Indeed, in the Italian keyboard layout, the key over tab is \.

In macOS it’s the same as in KDE: the shortcut is bound by default to ⌘+`, which of course it’s unusable in Italian keyboards (you should use a complex combination of keys only to insert the backtick ` character). You then have to configure the shortcut “Move focus to next window”, which is quite counterintuitive to me (I had always thought that it wasn’t possible in macOS to switch between windows of the same application if not by using the touchpad gesture or by pressing the down key after using the standard switcher):

Change it to something suitable for your keyboard layout. For the Italian layout I change it to ⌘+\:

And then you’re good to go! 🙂

KDE Plasma and Wayland: usability

It looks like KDE Plasma is getting usable with Wayland!

This is my current testing environment for this blog post:

Operating System: EndeavourOS
KDE Plasma Version: 5.24.5
KDE Frameworks Version: 5.94.0
Qt Version: 5.15.4
Kernel Version: 5.15.41-1-lts (64-bit)
Graphics Platform: Wayland
Processors: 8 × Intel® Core™ i7-8550U CPU @ 1.80GHz
Memory: 15,3 GiB of RAM
Graphics Processor: Mesa Intel® UHD Graphics 620

I had tested KDE Plasma with Wayland in the past, and the main problem I was experiencing, which made it unusable to me, was that I had to scale the display. I could scale the display, but the main problem was that, while KDE applications looked nice, the GTK applications looked blurred. This problem is still there, as you can see from this screenshot (here, I scaled the display to 150%):

You can see that the System settings dialog and Dolphin (in the background) look nice, but the EndeavourOS Welcome app and Firefox (in the background), which are GTK applications, look blurred!

Thus, I tried another way: I went back to 100% Display and tried to work on the Font HDPI scaling, though Plasma discourages doing that (it suggests using the display scaling). I tried with both 120 and 140 the result is satisfactory, as you can see from these screenshots:

IMPORTANT: You have to log out and log in to apply these changes. At least, I had to do that in my experiments.

There’s still one caveat to solve: GTK4 applications, like Gedit (the Gnome text editor) and Eye of Gnome (the Gnome image viewer), which, in this version of EndeavourOS, are already provided in their 42 version (using libadwaita). These applications are not considering font scaling. To solve that, you have to install Gnome Tweaks and adjust the “Scaling Factor” from there. Then, everything works also for those applications (Gedit is the one with “Untitled Document 1,” and Eye of Gnome is the dark window in the foreground):

With the Wayland session in Plasma, you can enjoy the default touchpad gestures (which, at the moment, are not configurable):

  • 4 Finger Swipe Left –> Next Virtual Desktop.
  • 4 Finger Swipe Right –> Previous Virtual Desktop.
  • 4 Finger Swipe Up –> Desktop Grid.
  • 4 Finger Swipe Down –> Available Window Grid.

Moreover, the scrolling speed for the touchpad can be configured (while, on X11, I wasn’t able to):

There are still a few strange things happening: the splash screen has the title bar and window buttons if you start Eclipse! 😀

I’ll try to experiment with this configuration also in other distributions.

Let’s cross our fingers! 😉