script: unison echo message only on errors

scripts/unison_backup.sh

@@ -3,13 +3,13 @@ tmp_file=$(mktemp)
 
 for profile in $@;
 do
-	res=$(${unison_exe} -batch $profile > ${tmp_file} 2>&1)
-	grep "Nothing to do: replicas have not changed since last sync" ${tmp_file} > /dev/null
+	res="$(${unison_exe} -batch $profile > ${tmp_file} 2>&1)"
 	file_sync=$?
 	
-	if [ ! $file_sync == 0 ];
+	if [ "$file_sync" -ne "0" ];
 	then
-		echo $(more ${tmp_file})
+		echo "return code $file_sync"
+		more ${tmp_file}
 	fi
 done