#!/bin/bash -x
# Set grub to boot into a different distro, and reboot unless -r
-# $0 DISTRO_NAME
+# $0 [DISTRO_NAME]
+# with no argument, print available distros
# DISTRO_NAME is based on the partition names in /boot. eg boot_debianjessie
###### end command line parsing #####
+if [[ ! $distro ]]; then
+ echo "available distros:"
+ btrfs subvolume list /boot | sed -rn 's/^.*boot_(.*)/\1/p'
+ exit 0
+fi
+
if ! btrfs subvolume list /boot | grep "_$distro$" &>/dev/null; then
echo "$0: error: _$distro$ not found in btrfs subvolume list /boot:"
btrfs subvolume list /boot