fix bugs, support multiple distros via subvolumes

[automated-distro-installer] / chboot

diff --git a/chboot b/chboot
new file mode 100755 (executable)
index 0000000..37d2516
--- /dev/null
+++ b/chboot
@@ -0,0 +1,48 @@
+#!/bin/bash -x
+
+# Set grub to boot into a different distro, and reboot unless -r
+# $0 DISTRO_NAME
+
+# DISTRO_NAME is based on the partition names in /boot. eg boot_debianjessie
+
+set -eE -o pipefail
+trap 'echo "$0:$LINENO:error: \"$BASH_COMMAND\" returned $?"' ERR
+
+[[ $EUID == 0 ]] || exec sudo "$BASH_SOURCE" "$@"
+
+reboot=true
+while [[ $1 == -* ]]; do
+    case $1 in
+        -r) reboot=false; shift ;;
+        --) break ;;
+    esac
+done
+
+
+distro=$1
+
+###### end command line parsing #####
+
+if ! btrfs subvolume list /boot | grep "_$distro$" &>/dev/null; then
+    echo "$0: error: _$distro$ not found in btrfs subvolume list /boot:"
+    btrfs subvolume list /boot
+    exit 1
+fi
+
+e() { echo "$@"; "$@"; }
+
+boot_dev=$(mount | sed -rn "s#^(\S+) on /boot .*#\1#p")
+
+mount_point=$(mktemp -d)
+
+e mount -o subvol=boot_$distro $boot_dev $mount_point
+
+boot_disk=${boot_dev%%[0-9]*}
+
+# arch doesn't have $mount_point/grub/device.map, accoring to the grub manual,
+# it just generates one if the file doesn't exist.
+# https://www.gnu.org/software/grub/manual/html_node/Device-map.html
+e grub-bios-setup -d $mount_point/grub/i386-pc -s -m $mount_point/grub/device.map $boot_disk
+
+e umount $mount_point
+e rmdir $mount_point