NixOS

A reliable, step-by-step guide to bring a VirtualBox/VMware .ova into QEMU/KVM, with both GUI and CLI paths—and fixes for the most common pitfalls.Contents Prerequisites 1) Extract the OVA 2) Convert VMDK → QCOW2 3) Create the VM in virt-manager (GUI) 4) Alternative: virt-install (CLI) 5) Common gotchas & fixes Quick troubleshooting checklist Prerequisites QEMU/KVM, libvirt, and virt-manager installed on the host. User is allowed to manage libvirt (typically being in the libvirt/libvirtd and kvm groups). Enough disk space to hold the converted image (QCOW2). 1) Extract the OVA An OVA is a tar archive containing an .ovf (metadata) and one or more .vmdk disks. ...

What started as a quick VirtualBox install turned into a multi‑headed boss fight: USB errors, a sulking kernel driver, a turf war with KVM, and even a Nix syntax bite. Here’s the complete journey and the fixes that finally made my VM boot. Head #1 — USB devices wouldn’t enumerate Can't enumerate USB devices Could not load the Host USB Proxy service: VERR_NOT_FOUND Root cause: Host USB support + Extension Pack missing, and the user not in vboxusers. ...

If you’ve ever felt overwhelmed by NixOS commands, flakes, or the dreaded garbage collection panic, this guide is for you. It’s not just a cheatsheet—it’s a practical survival kit for running NixOS with flakes, keeping your system clean, and always having a rollback strategy when things go sideways. 🖥️ NixOS Essentials Task Command Show version nixos-version Edit config (classic) sudo nano /etc/nixos/configuration.nix Rebuild + switch sudo nixos-rebuild switch Build only (no switch) sudo nixos-rebuild build Roll back last rebuild sudo nixos-rebuild switch --rollback List generations sudo nix-env --list-generations --profile /nix/var/nix/profiles/system ⚡ Flakes Basics Task Command Init flake nix flake init -t templates#nixos Show flake outputs nix flake show Update all inputs nix flake update --commit-lock-file Update one input nix flake lock --update-input nixpkgs --commit-lock-file Build system sudo nixos-rebuild build --flake .#<hostname> Switch system sudo nixos-rebuild switch --flake .#<hostname> Boot (safe) sudo nixos-rebuild boot --flake .#<hostname> 🔄 Safe Updates & Rollbacks Keeping your system updated is great… until it doesn’t boot. Here’s how to avoid disasters. ...