-# Runs amdevcheck to find out if a particular device is usable. Finds the
-# config name based on pwd, so run it from the config directory. The sole
-# argument should be the device name to check. Note that amdevcheck can FP
-# on device status, since some devices can't differentiate between device
-# problems and an unlabeled volume.
+# Invoke amdevcheck to determine whether the device is ready for use.
+#
+# @return 0 if a tape is loaded or error
+# @return 1 if a tape is tape offline or busy
+#
+# @side-effect: $amdevcheck_message is the contents of all MESSAGE lines from
+# amdevcheck, suitable for use in higher-level error messages