proxmox import vm from kvm

Create a new VM in the web interface (leave other settings as default)
copy VM disk to proxmox (ex. using terminal) and import it to newly created VM machine
qm importdisk machine_id_number /var/lib/vz/images/file.qcow local-zfs
qm rescan

Go to your new created VM in the proxmox web interface.
Go to the Hardware section of the newly created VM in the Proxmox web interface
Look for the Unused Disk and select it.
Then you have to add the disk by clicking on Edit on the top.

Reducing the size of a QEMU virtual disk (thin disk)

On all mounting points
dd if=/dev/zero of=/nul;sync;sync;sync;rm -f /nul;sync

Stop VM

Convert disk

qemu-img convert -O qcow2 -c disk1.qcow disk1.new.qcow

AC power notify

upower -i $(upower -e | grep '_AC') | grep "online"

Unboud (DNS) – listen on IPv4 only

Add to /etc/unbound/unbound.conf

server:
interface: 0.0.0.0

TMUX

split-window -h: Ctrl+b %

split-window -v: Ctrl+b ”

wrong Video codec on Opera Linux Mint

install chromium and

mv /usr/lib/x86_64-linux-gnu/opera/libffmpeg.so /usr/lib/x86_64-linux-gnu/opera/libffmpeg.so.orig
ln -s /usr/lib/chromium/libffmpeg.so /usr/lib/x86_64-linux-gnu/opera/

snapshots of UEFI libvirt-based (KVM) virtual machines

Shut down VM and then

Listing
qemu-img snapshot -l <file>.qcow2

Create
qemu-img snapshot -c <snap-name> <file>.qcow2

Revert to 
qemu-img snapshot -a <snap-name> <file>.qcow2

Delete
qemu-img snapshot -d <snap-name> <file>.qcow2

USB NIC reset

lsusb 
Bus 002 Device 002: ID 8087:8000 Intel Corp. Integrated Rate Matching Hub 
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub 
Bus 001 Device 002: ID 8087:8008 Intel Corp. Integrated Rate Matching Hub 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub 
Bus 004 Device 003: ID 0bda:8153 Realtek Semiconductor Corp. RTL8153 Gigabit Ethernet Adapter 
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub 
Bus 003 Device 003: ID 04f2:b477 Chicony Electronics Co., Ltd HP HD Webcam 
Bus 003 Device 002: ID 0424:2514 Microchip Technology, Inc. (formerly SMSC) USB 2.0 Hub 
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

then
usbreset 0bda:8153

Rsync copy

rsync -azP -e "ssh -p PORT_NUMBER" source destination

KVM Snapshot with only one disk

virsh snapshot-create-as --domain ${VM}
--name "backup-${VM}" \
--atomic \
--disk-only \
--no-metadata \
--diskspec vda,file=${SNAP}/backup-snapshot-${VM} \
--diskspec vdb,snapshot=no