Categoria: linux

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Timeout of grub boot

You have to edit grub in /etc/default (i.g. with nano: sudo nano /etc/default/grub)

not only modifying this line: GRUB_TIMEOUT=3

but also adding (after that) this one: GRUB_RECORDFAIL_TIMEOUT=$GRUB_TIMEOUT

Of course after these changes you have to do a 

sudo update-grub

as explained here.

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mozilla keyring problem

I had this problem:

E: https://packages.mozilla.org/apt mozilla InRelease is not (yet) available (The following signatures couldn't be verified because the public key is not available: NO_PUBKEY C0BA5CE6DC6315A3)

After many attempts it seems solved removing (renaming) the file .org.kde.neon.packages.mozilla.org.sources in /etc/apt/sources.list.d/

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strange behavior in Vivaldi

If you get a pop-up window to unlock Vivaldi profile, and you share your Vivaldi profile between different Linux installation (devices), you could try to copy the folder .local/share/kwalletd from the working installation of Vivaldi to the other ones.

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to install an appimage

Make an appimage executable is absolutely easy. But less easy is to associate that application with its mime-type files. Especially if that type of file doesn’t exist already on your system.

A very easy way, then, is to go to the appimage folder and, in a terminal, do 

(sudo) ./appimage-name install

With this command all will be ready, correctly set, as if that application wouldn’t be an appimage, but a “regular” one.

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chroot in linux

Chroot is a very useful feature in Linux systems: you can update a Linux installation on your PC not within that installation, as usually we can do, but from another installation.

I.g. if you have Linux1 on /dev/sda2 and Linux2 on /dev/sda3 and you cannot login into Linux2, you can try to solve the problem by doing an update of Linux2 from Linux1. Using chroot.

There are very good guides on the web, but, let us repeat the essential steps

  • first of all be sure of the correct name of the partition you want chroot in (i.g. /dev/sda3, or /dev/sdb2)
  • create a /mnt where you will mount that installation, i.g. /mnt/chroot
  • mount that installation in /mnt/chroot: sudo mount -t ext4 /dev/sda3 /mnt/chroot (note that etx4 is if that is the filesystem, but it could be btrfs as well or another filesystem)
  • mount efi partion (if you have efi): sudo mount -t vfat /dev/sda1 /mnt/chroot/boot/efi/
  • mount virtual folders of that installation: for i in dev proc sys run; do sudo mount --bind /$i /mnt/chroot/$i; done
  • Do the chroot: sudo chroot /mnt/chroot

What you do now, within the terminal where you did the chroot is what you could do if you were in that installation (Linux2).
Typically you should do these commands

  • apt update (without sudo before apt: you are already acting as superuser)
  • apt upgrade (or apt full-upgrade)
  • update-grub

Afterwards you can exit with:

  • for i in /dev /proc /sys /run /; do sudo umount -l /mnt/chroot/$i; done
  • and: sudo umount /dev/sda2 /mnt/chroot/boot/efi/
  • and: sudo umount /dev/sda3 /mnt(chroot

Note that these last two commands could be not necessary.

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monitor hdmi never sleeping

It’s a known bug in Linux: when a monitor is connected with an hdmi cable, there are “sleeping” problems (monitor not sleeping as expected or sleeping but with annoying error/crash messages).

While we expect an hardware solution, a scripting workaround could be this code

bash -c 'sleep 0.1 && xset dpms force off'