Categoria: sistema operativo

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Verify a KDE-Neon iso with a sig file

You have first of all to install the public-key of KDE-Neon:

  • downloading it (it is a text file such as armored-keys.asc)
  • and installing it gpg –import [your-downloaded-public-key-file]

Then you have to go into the folder where are both iso and sig files and give this command

gpg --verify [your-iso-file-name].iso.sig

You should see something like:

gpg: assuming signed data in 'neon-user-20200813-1119.iso'
gpg: Signature made �� 16:40:21 PKT �� 13 �������� 2020
gpg:                using RSA key 348C8651206633FD983A8FC4DEACEA00075E1D76
gpg: Good signature from "KDE neon ISO Signing Key <neon@kde.org>" [unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: 348C 8651 2066 33FD 983A  8FC4 DEAC EA00 075E 1D76

Here more.

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MIDI keyboard and Linux

To get your MIDI keyboard working in Linux, you should do something like the following steps:

1) install Rosegarden, which automatically install jack and the related software in particular Qjackqtl (jack GUI). Maybe you could install directly Qjackqtl…

2) add your user to the audio group

sudo usermod -a -G audio <your_user_name>

3) install Qsynth,
4) do the following terminal command

sudo apt update; sudo apt full-upgrade -y; sudo apt install -y pipewire-audio-client-libraries libspa-0.2-bluetooth libspa-0.2-jack wireplumber pipewire-media-session-; sudo cp /usr/share/doc/pipewire/examples/alsa.conf.d/99-pipewire-default.conf /etc/alsa/conf.d/; sudo cp /usr/share/doc/pipewire/examples/ld.so.conf.d/pipewire-jack-*.conf /etc/ld.so.conf.d/; sudo ldconfig; sudo apt remove -y pulseaudio-module-bluetooth; systemctl --user --now enable wireplumber.service

Musescore and a MIDI keyboard

To get Musescore able to record from a MIDI keyboard I had to use the 4 release, so far with an appimage from their website.

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grub rescue

It could happen that your PC, after some operations (i.g. with gdisk) doesn’t start booting and you are therefore in grub rescue prompt. A very unpleasant situation.

The steps to follow are:

  1. see what are the partitions, with the command ls
    • you should see something like: (hd0)(hd0,msdos1)(hd0,msdos2)(hd1)(hd1,gpt1)
  2. understand what is the right partition to boot (i.g. hd0,gpt2):
    • you can list a single partition to see what it contains, with the command ls (hd0,gpt2). You should be able to see if a partition is the right one.
  3. give the command set prefix=(hd0,gpt2)/boot/grub
  4. give the command set root=(hd0,gpt2)/ root=/dev/sda2 (if the right partition is hd0,gpt2 the name is /dev/sda2, if it was hd1,gpt3 it would be /dev/sdb3)
  5. give the command insmod normal
  6. give the command: normal (or boot)

In this way the system should start with the expected partition.

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boot useful tips

  1. It is not necessary to start booting with EFI if you have GPT partitions (you could choose to have legacy boot with GPT partitions).
  2. It is not necessary that EFI partition be at the start of a disk: it could be in every place, provided that it has a) boot (esp) flags, and b) at least 110mb of space.
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Flatpak bad installation

It could happen that a flatpak installation, from a link, goes bad and from a GUI you can’t fix the problem. In this case you can try with: sudo flatpak repair in a terminal.

At least, this was my experience with Bottles.

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System not starting after upgrading to Ubuntu 22.04

After upgrading Ubuntu from 20.04 to 22.04 it can happen that you cannot start the desktop: emergency mode.

In some case it could be happened that fstab was modified and the efi partition is set with a wrong UUID. Therefore you can try to change, in your fstab file, the efi UUID (i.g. copying it from a working installation).

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old windows releases in virtualbox

It is possible to virtualize old windows releases, such as windows 3.1, windows 98 (download here), or windows ME and the like.

But there are severe limitations: your host keyboard and mouse will be unavailable, and no link will be possible between the host and the guest system.

The reason is that in that old systems you cannot install the virtualbox guest additions.