+#!/bin/bash
+
+# input eg: /dev/sda1 or /dev/sda
+# output: /dev/disk/by-id/model+serial, or if no link exists, the same as input
+
+short_dev=$1 # i.e.
+
+# devices are identified by model+serial num,
+# and wwn. model+serial gives me more info, so use that.
+shopt -s extglob
+for id in /dev/disk/by-id/!(wwn*); do
+ [[ -e $id ]] || break # if we matched nothing
+ if [[ $(readlink -f $id) == "$short_dev" ]]; then
+ printf '%s\n' "$id"
+ exit
+ fi
+done
+# a vm may not have a by-id link.
+printf '%s\n' "$short_dev"