add some useful error messages

zb-cleanup

@@ -40,7 +40,7 @@ done |sort -n | while read l ; do
 
 	if [ "$curtime" -lt "$max_age" ] ; then
 		#too old
-		zfs destroy "$snapname"
+		zfs destroy "$snapname" || echo "$0: zfs destroy $snapname failed" >&2
 		continue
 	fi
 
@@ -52,7 +52,7 @@ done |sort -n | while read l ; do
 	#if it's too dense, delete the closer snapshot
 	if [ $(( ($density*($curtime-$lasttime))/($timenow-$lasttime) )) -lt 100 ]
 	then
-		zfs destroy "$snapname"
+		zfs destroy "$snapname" || echo "$0: zfs destroy $snapname failed" >&2
 	else
 		lasttime="$curtime"
 	fi

zb-pull

@@ -63,6 +63,8 @@ else
 	ret=$?
 fi
 
+[ "$ret" != 0 ] && echo "pulling to ${local_zfs} failed" >&2
+
 #in some cases and on some setups (Sun_SSH) when `zfs recv` fails, ssh ignores
 #the SIGPIPE and the connection hangs there forever, somehow. This fixes the
 #issue by killing all children that were possibly spawned by this shell.