Ubuntu Jammy casualties: dotnet

Before I upgraded to Ubuntu 22.04 (Jammy), I had dotnet 5 and 6 installed, rather out of interest, than doing any serious programming.

As far as I can remember, I originally had installed the Snap version of dotnet, but had troubles installing any dotnet packages or templates, so I had switched to the “native” version of dotnet, probably using the dotnet-install.sh variant – I’m not sure.

Upgrading to 22.04 seems to have uninstalled dotnet 5, as it is out of support, and weird things happened to the dotnet 6 installation:

Running

dotnet new -i Avalonia.Templates

did not install the expected templates, but rather immediately returned the error message

The application ‘new’ does not exist

Further, the command dotnet --info listed two 6.0 runtimes, but did not know of any previously installed SDKs.

After uninstalling and re-installing and uninstalling the dotnet6 package, the command dotnet was still there, but did not do anything useful.

$ dotnet --list-sdks
A fatal error occurred. The folder [/usr/lib/dotnet/dotnet6-6.0.108/host/fxr] does not exist

This error message got me to dotnet/core Issue 5746 (dealing with .Net Core 3 on CentOS though), where a comment states

This can happen if dotnet-host and dotnet-hostfxr-3.1 are conflicting,

So I queried apt for the list of installed dotnet packages

$ apt list | grep dotnet

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

dotnet-apphost-pack-5.0/now 5.0.17-1 amd64 [installed,local]
dotnet-apphost-pack-6.0/jammy-updates,jammy-security,now 6.0.109-0ubuntu1~22.04.1 amd64 [installed,auto-removable]
dotnet-host/jammy-updates,jammy-security 6.0.109-0ubuntu1~22.04.1 amd64 [upgradable from: 6.0.108-0ubuntu1~22.04.1]
dotnet-hostfxr-5.0/now 5.0.17-1 amd64 [installed,local]
dotnet-hostfxr-6.0/jammy-updates,jammy-security,now 6.0.109-0ubuntu1~22.04.1 amd64 [installed,auto-removable]
dotnet-runtime-6.0/jammy-updates,jammy-security 6.0.109-0ubuntu1~22.04.1 amd64
dotnet-runtime-deps-5.0/now 5.0.17-1 amd64 [installed,local]
dotnet-sdk-6.0-source-built-artifacts/jammy-updates,jammy-security 6.0.109-0ubuntu1~22.04.1 amd64
dotnet-sdk-6.0/jammy-updates,jammy-security 6.0.109-0ubuntu1~22.04.1 amd64
dotnet-targeting-pack-5.0/now 5.0.0-1 amd64 [installed,local]
dotnet-targeting-pack-6.0/jammy-updates,jammy-security,now 6.0.109-0ubuntu1~22.04.1 amd64 [installed,auto-removable]
dotnet-templates-6.0/jammy-updates,jammy-security,now 6.0.109-0ubuntu1~22.04.1 amd64 [installed,auto-removable]
dotnet6/jammy-updates,jammy-security 6.0.109-0ubuntu1~22.04.1 amd64
libgtk-dotnet3.0-cil-dev/jammy 2.99.3-4build1 amd64
libgtk-dotnet3.0-cil/jammy 2.99.3-4build1 amd64

So I manually uninstalled all remaining dotnet packages

$ sudo apt-get remove dotnet-hostfxr-5.0
$ sudo apt autoremove

until the dotnet command was no longer recognized. From this clean state, I ran

$ sudo apt install dotnet6

and got a brand-new dotnet 6 environment and even a new application.

$ dotnet --info
.NET SDK (reflecting any global.json):
 Version:   6.0.109
 Commit:    58a93139d8

Runtime Environment:
 OS Name:     ubuntu
 OS Version:  22.04
 OS Platform: Linux
 RID:         ubuntu.22.04-x64
 Base Path:   /usr/lib/dotnet/dotnet6-6.0.109/sdk/6.0.109/

global.json file:
  Not found

Host:
  Version:      6.0.9
  Architecture: x64
  Commit:       163a63591c

.NET SDKs installed:
  6.0.109 [/usr/lib/dotnet/dotnet6-6.0.109/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 6.0.9 [/usr/lib/dotnet/dotnet6-6.0.109/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 6.0.9 [/usr/lib/dotnet/dotnet6-6.0.109/shared/Microsoft.NETCore.App]

File Organizers: Calibre

A long time ago, I had a look at Calibre to organize my e-books, but chose not to use it mainly because of one issue: Calibre uses its own directory structure to organize its e-books (library/author/title (id)), and also renames the files accordingly (truncated title - author.extension).

How should I ever find a book again, I thought, if the tool ignores my structure of sorting files? After all, I already created some kind of order on my file system, so that I should know where my books are.

Well, in the course of cleaning up a soon-to-be shut-down machine, I noticed that my e-book collection instead was really a huge mess, spread over several machines, discs, and directories, full of duplicates and copies – recognizable by file name or file size.

So, let’s throw it all on Calibre.

The nice thing about Calibre is that it stores its metadata not in the e-books, but in a local SQLite database and a metadata.opf OPF file for every book.

Also, using tags to organize books is more flexible and powerful as compared to the tree-like directory hierarchy of traditional file systems.

Still, I wanted to keep the original filename of any catalogued e-book, so I added the GetFileName plugin which automatically adds the original filename in a separate user-defined column.

To keep track of all the books I always wanted to read, and those I have already read, I installed the Reading List plugin.

Since Calibre warns you if you want to import a book already imported, and I always ignore those warnings, a lot of duplicates are going to end up in my e-book library. That’s where the Find Duplicates plugin is going to be helpful in the future.

Until then, a generic [todo] tag adorns all my Calibre books until the metadata is cleaned up.

Though still early in my book-cataloguing adventure, I already stumble across problems I still need to figure out.

  • How do you handle different spellings of an author’s name (plain name, with middle initial, with middle name) or pseudonyms?
  • How do you import HTML books spread over several pages?
  • How do you handle e-books split into chapter-wise PDFs?

Not all updates can be installed

If you run Ubuntu, you’ll notice that every now and then the Software Updater will provide you with a notification

Updated software is available for this computer. Do you want to install it now?

Except, when it does not, and instead displays a dialog

Software Updater: Not all updates can be installed

with a set of rather unintuitive buttons.

What is most disturbing is the list of possible causes, when it’s just a piece of software that checked all kinds of error conditions and should know what went wrong, and should be able to detail the error condition that prevents it from resuming its task, rather than the lazy “An error occurred”.

So I started to track the message down, and found:

  • Software Updater is a Python/GTK application residing in /usr/bin/update-manager
  • The application imports code from the UpdateManager package under /usr/lib/python3/dist-packages/UpdateManager
  • There, the MyCache class in Core/MyCache.py checks for various error conditions, and presents above dialog if something went wrong

It should be easy to adapt the code to display those error conditions. After a bit of trial and error, my version of the MyCache class displayed what kept the Software Updater from updating:

$ ./CheckUpdateManager.py
initializing
checking
would delete nodejs-doc
that's all

After removing the listed package

$ sudo apt-get remove nodejs-doc

Software Updater displayed its usual window of updatable software components.

The script CheckUpdateManager.py is available in my Python repository.

Disabling Loopback for Logitech G432 on Ubuntu

My old Logitech headset died a number of deaths (headband broken, cushion torn, finally cable broken), so I got myself a G432.

Unfortunately, using it in Teams under Ubuntu, I experienced an irritating loopback. Quickly took to the internets, but AskUbuntu was only of limited help.

For example, one answer suggested to use alsamixer, but that only completely muted the headset, not only the microphone loopback.

Another answer pointed me to a tool called HeadsetControl which allows exactly the control I wanted, and its Readme file even lists the model I have. Hurray.

I followed the instructions to install:

sudo apt-get install build-essential git cmake libhidapi-dev
git clone https://github.com/Sapd/HeadsetControl && cd HeadsetControl
mkdir build && cd build
cmake ..
make
sudo make install

After installation, I ran

$ headsetcontrol -?
Found Logitech G432/G433!
Supported capabilities:

* sidetone

And tried to set “sidetone” to zero:

headsetcontrol -s 0
Found Logitech G432/G433!
Failed to open requested device.
HID Error: (null)

Apparently, headsetcontrol requires sudo:

sudo headsetcontrol -s 0
Found Logitech G432/G433!
Success!

No more loopback!

Wordle cheat script

An article on The Register linked to a GitHub shell script version of Wordle, and what caught my eye was that apparently a Linux installation contains a dictionary of English words in the file /usr/share/dict/words.

If you are stuck in your daily Wordle, you can use this file to figure out solutions:

CommandPurpose
grep -E '^([a-zA-Z]){5}$' /usr/share/dict/wordscollect all 5-letter words
tr '[a-z]' '[A-Z]'convert words to upper case
grep 'RU...'filter words for matching (green) letters
grep '[E]'filter words for letters in the wrong spot (yellow)
grep -v '[ASD]'exclude known wrong letters (dark grey)

Combine the commands (the last 3 are optional) with the respective letters filled in, separated by the pipe “|”:

$ grep -E '^([a-zA-Z]){5}$' /usr/share/dict/words | tr '[a-z]' '[A-Z]' | grep 'RU.E.' | grep -v '[TASDLMN]'
RUPEE

Switching Sound Output between Headset and Speakers

How do you change the sound device a particular application is using for its audio output? I never bothered to think about this question, until the times of the shared home office.

True, in Windows you can change the default sound device, and an application that is started afterwards will use that device. But changing the sound device for a running application? It seems there is no built-in way to do that.

For Windows 7 and higher, I found the SoundSwitch applet (GitHub), which does just that. Located in the notification area, it lets you select the sound device the current application outputs its audio to. Simply click on its icon and select the device, or press a customizable hotkey.

For Ubuntu, I found Sound Switcher Indicator (GitHub, Blog). Upon installation, it can be accessed from the indicator area, and allows the selection of audio input and output devices.

Problems solved 😉

Epilogue

During preparation of this post, I tried to figure out how SoundSwitch actually switches the audio device.

It turns out that it uses the function call SetPersistedDefaultAudioEndpoint() which is also used by an application called EarTrumpet (GitHub) that tags itself as “Volume control for Windows”, but also seems to allow switching audio devices.

A review of this application by Scott Hanselman indicates that the method and its interface are not officially documented:

Internal Audio Interface: IAudioPolicyConfigFactory

Gets them access to new APIs (GetPersistedDefaultAudioEndpoint / SetPersistedDefaultAudioEndpoint) in RS4 that let’s them ‘redirect’ apps to different playback devices. Same API used in modern sound settings.

Code here with no public API yet?

Renaming files after their time stamp in Ubuntu

Downloading data files from certain web sites, the data files usually either are already named after their creation timestamp, or they end with subsequent numbering (1), (2), … in their names.

To rename such numbered files, I found that the date -r command displays a file’s modification timestamp, which can be formated with the +format option:

date -r somefilename.txt +%Y%m%d

To iterate over all downloaded files, I use

for f in file*name*pattern* do

Putting it all together, I came up with the one-liner

for f in pattern*; do mv $f `date -r $f +filename_%Y%m%d`.csv; done

Fixing the –startvm Error Message

After upgrading Ubuntu from 18.04 to 20.04, I noticed that my VM .desktop shortcut throws the error message

–startvm is an option for the VirtualBox VM runner (VirtualBoxVM) application, not the VirtualBox Manager.

Before the upgrade, it simply started the virtual machine referenced as parameter value.

It seems that VirtualBox moved the --startvm parameter from the previous VirtualBox executable to VirtualBoxVM. More infos and links can be found in this VirtualBox ticket.

The (easy) solution was to open the .desktop file in an editor, and change the line

Exec=/usr/lib/virtualbox/VirtualBox ....

to

Exec=/usr/lib/virtualbox/VirtualBoxVM ....

AutoMySQLBackup Warning

When I replaced my original Ubuntu server with the (then) more current Ubuntu 18.04, I also moved MySQL databases and wanted to have them backed up regularly.

I had used the script AutoMySQLBackup which did the job fine, and installed it on the new machine. (When I first found the script, I adapted for PowerShell on Windows it to backup my SQL Server databases)

On the new machine, however, the tool mysqldump issued the warning

[Warning] Using a password on the command line interface can be insecure.

The change seems to have been introduced in MySQL 5.6, and the solution to the warning is documented in the MySQL 5.6 Reference Manual. There are also answers on SO regarding the warning

mysql_config_editor set --login-path=local --host=localhost --user=username --password

mysql --login-path=local -e "statement"

 

I guess I tried to change the .sh script to call mysqldump with –login-path instead of –user/–password.

As the original script is not maintained anymore, I found this fork of AutoMySQLBackup which is still active, and also documents the use of –login-path.

Opening .url Files in Ubuntu

When browsing the web with Chrome for Android, I save the URLs on my Nextcloud server by sharing using the Nextcloud App. Each URL is then stored as a .url file looking like this

[InternetShortcut]
URL=https://devio.wordpress.com/

Today I noticed that those .url files cannot be opened on Ubuntu, i.e. a double-click won’t start a browser with the contained URL.

Instead, I get a an error dialog

Could not display “<HTML page title>.url”.

There is no application installed for “Internet shortcut” files.
Do you want to search for an application to open this file?

No     Yes

Screenshot from 2020-03-22 07-40-58.png

Clicking the Yes button, a toast message appears

mimetype required.png

which you have to click before it disappears, which finally opens the software installer:

unable to find software.png

Not good.

Surprisingly, Firefox does not register itself as an application to handle the .url file extension on Ubuntu. It also does not know that the Windows Firefox would know how to open the file.

More surprisingly, Ubuntu knows that .url files are “Internet shortcut” files, and have the associated MIME type application/x-mswinurl.

So I had to solve two problems:

  • Retrieve the URL stored in a .url file
  • Start Firefox using this URL using Ubuntu’s MIME type handling

Retrieving the URL stored in a .url file

As shown above, a .url file is simply a text file in .ini format. In it’s simplest form, it contains a section [InternetShortcut] with a single Key “URL=”. The key’s value is the URL to navigate to.

With a little help from askubuntu, I figured out the command to extract the URL value

grep -Po 'URL=\K[^ ]+' *.url

Using the result of the grep operation as argument for firefox would look something like this:

firefox `grep -Po 'URL=\K[^ ]+' "$1"`

After a bit of digging, I found how you can manually add MIME type handlers in Ubuntu. Following those instructions, I created a file

/usr/share/applications/mswinurl.desktop

(you need sudo in this directory) with the following content (spoiler: don’t copy this yet!):

[Desktop Entry]
Name=Firefox Shortcut
GenericName=Firefox Shortcut

Type=Application
Exec=firefox `grep -Po 'URL=\K[^ ]+' %U`
TryExec=firefox
MimeType=application/x-mswinurl;
Icon=firefox

However, this did not work as intended, as I got an error message complaining about the backtick `. So, if I cannot have shell operations in the .desktop file, let’s create a batch file

/usr/local/bin/runurl

and place the shell magic there:

firefox `grep -Po 'URL=\K[^ ]+' "$1"` &

Don’t forget to make the batch file executable using

sudo chmod 755 runurl

and reference the runurl script rather than Firefox in /usr/share/applications/mswinurl.desktop:

[Desktop Entry]
Name=Firefox Shortcut
GenericName=Firefox Shortcut

Type=Application
Exec=runurl %U
TryExec=firefox
MimeType=application/x-mswinurl;
Icon=firefox

After creating the file, run

 sudo update-desktop-database

to register the new .desktop file.

Double-clicking a .url file now opens the URL in a new Firefox tab.