119c8f91e7
Setting nixosVersion to something custom is useful for meaningful GRUB menus and /nix/store paths, but actuallly changing it rebulids the whole system path (because of `nixos-version` script and manual pages). Also, changing it is not a particularly good idea because you can then be differentitated from other NixOS users by a lot of programs that read /etc/os-release. This patch introduces an alternative option that does all you want from nixosVersion, but rebuilds only the very top system level and /etc while using your label in the names of system /nix/store paths, GRUB and other boot loaders' menus, getty greetings and so on.
141 lines
4.1 KiB
Bash
141 lines
4.1 KiB
Bash
#! @bash@/bin/sh -e
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shopt -s nullglob
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export PATH=/empty
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for i in @path@; do PATH=$PATH:$i/bin; done
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usage() {
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echo "usage: $0 -t <timeout> -c <path-to-default-configuration> [-d <boot-dir>] [-g <num-generations>]" >&2
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exit 1
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}
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timeout= # Timeout in centiseconds
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default= # Default configuration
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target=/boot # Target directory
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numGenerations=0 # Number of other generations to include in the menu
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while getopts "t:c:d:g:" opt; do
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case "$opt" in
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t) # U-Boot interprets '0' as infinite and negative as instant boot
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if [ "$OPTARG" -lt 0 ]; then
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timeout=0
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elif [ "$OPTARG" = 0 ]; then
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timeout=-10
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else
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timeout=$((OPTARG * 10))
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fi
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;;
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c) default="$OPTARG" ;;
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d) target="$OPTARG" ;;
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g) numGenerations="$OPTARG" ;;
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\?) usage ;;
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esac
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done
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[ "$timeout" = "" -o "$default" = "" ] && usage
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mkdir -p $target/nixos
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mkdir -p $target/extlinux
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# Convert a path to a file in the Nix store such as
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# /nix/store/<hash>-<name>/file to <hash>-<name>-<file>.
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cleanName() {
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local path="$1"
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echo "$path" | sed 's|^/nix/store/||' | sed 's|/|-|g'
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}
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# Copy a file from the Nix store to $target/nixos.
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declare -A filesCopied
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copyToKernelsDir() {
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local src=$(readlink -f "$1")
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local dst="$target/nixos/$(cleanName $src)"
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# Don't copy the file if $dst already exists. This means that we
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# have to create $dst atomically to prevent partially copied
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# kernels or initrd if this script is ever interrupted.
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if ! test -e $dst; then
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local dstTmp=$dst.tmp.$$
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cp -r $src $dstTmp
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mv $dstTmp $dst
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fi
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filesCopied[$dst]=1
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result=$dst
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}
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# Copy its kernel, initrd and dtbs to $target/nixos, and echo out an
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# extlinux menu entry
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addEntry() {
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local path=$(readlink -f "$1")
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local tag="$2" # Generation number or 'default'
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if ! test -e $path/kernel -a -e $path/initrd; then
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return
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fi
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copyToKernelsDir "$path/kernel"; kernel=$result
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copyToKernelsDir "$path/initrd"; initrd=$result
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if [ -n "@kernelDTB@" ]; then
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# XXX UGLY: maybe the system config should have a top-level "dtbs" entry?
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copyToKernelsDir $(readlink -m "$path/kernel/../dtbs"); dtbs=$result
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fi
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timestampEpoch=$(stat -L -c '%Z' $path)
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timestamp=$(date "+%Y-%m-%d %H:%M" -d @$timestampEpoch)
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nixosLabel="$(cat $path/nixos-version)"
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extraParams="$(cat $path/kernel-params)"
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echo
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echo "LABEL nixos-$tag"
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if [ "$tag" = "default" ]; then
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echo " MENU LABEL NixOS - Default"
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else
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echo " MENU LABEL NixOS - Configuration $tag ($timestamp - $nixosLabel)"
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fi
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echo " LINUX ../nixos/$(basename $kernel)"
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echo " INITRD ../nixos/$(basename $initrd)"
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if [ -n "@kernelDTB@" ]; then
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echo " FDTDIR ../nixos/$(basename $dtbs)"
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fi
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echo " APPEND systemConfig=$path init=$path/init $extraParams"
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}
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tmpFile="$target/extlinux/extlinux.conf.tmp.$$"
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cat > $tmpFile <<EOF
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# Generated file, all changes will be lost on nixos-rebuild!
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# Change this to e.g. nixos-42 to temporarily boot to an older configuration.
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DEFAULT nixos-default
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MENU TITLE ------------------------------------------------------------
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TIMEOUT $timeout
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EOF
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addEntry $default default >> $tmpFile
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if [ "$numGenerations" -gt 0 ]; then
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# Add up to $numGenerations generations of the system profile to the menu,
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# in reverse (most recent to least recent) order.
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for generation in $(
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(cd /nix/var/nix/profiles && ls -d system-*-link) \
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| sed 's/system-\([0-9]\+\)-link/\1/' \
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| sort -n -r \
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| head -n $numGenerations); do
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link=/nix/var/nix/profiles/system-$generation-link
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addEntry $link $generation
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done >> $tmpFile
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fi
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mv -f $tmpFile $target/extlinux/extlinux.conf
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# Remove obsolete files from $target/nixos.
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for fn in $target/nixos/*; do
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if ! test "${filesCopied[$fn]}" = 1; then
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echo "Removing no longer needed boot file: $fn"
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chmod +w -- "$fn"
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rm -rf -- "$fn"
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fi
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done
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