nix run github:m00k/nixos?dir=shells/install
# file:https:///home/m00k/workspace/nixos?dir=shells/install&ref=refs/heads/f/installer&rev=d958411a535571130f1ca413dd9afdfb790640ce

nix flakes show # list flake outputs
nixos-rebuild dry-activate --flake ./#$HOSTNAME
nixos-rebuild dry-build --flake ./#$HOSTNAME
nixos-rebuild build-vm --flake ./#$HOSTNAME
./result/bin/run-$USER-vm # run vm (replace $USER)

# Update flake.lock
nix flake update
# Or replace only the specific input, such as home-manager:
nix flake lock --update-input home-manager
# Apply the updates
sudo nixos-rebuild switch --flake ./#$HOSTNAME
# Or activate only after reboot
sudo nixos-rebuild boot --flake ./#$HOSTNAME #

nix-env --list-generations --profile /nix/var/nix/profiles/system
nix-env --delete-generations +10 --profile /nix/var/nix/profiles/system # keep last 10 (plus newer than current)
nix-env --delete-generations 30d --profile /nix/var/nix/profiles/system # remove older than 30 days

# use the previous generation
nix-env --rollback --profile /nix/var/nix/profiles/system

# use specific version
nix-env --switch-generation 53 --profile /nix/var/nix/profiles/system # switch to generation no. 53
nix-env --delete-generations 54 --profile /nix/var/nix/profiles/system # delete generation no. 54

# remove old generations from boot menu
nixos-rebuild boot

# list entries
ll /boot/loader/entries

# UEFI or Legacy boot?
[ -d /sys/firmware/efi/efivars ] && echo "UEFI" || echo "Legacy"