betelgeuse@pena ~/gsoc/libbash $ ./ast_printer -e '"' -memory-(1) : error 5 : Unexpected token, at offset -1 near [Index: 0 (Start: 140166812-Stop: 140166812) ='"', type<144> Line: 1 LinePos:-1] : missing elements... (LIST (COMMAND Tree Error Node)) betelgeuse@pena ~/gsoc/libbash $ echo $? 0 We should exit with EXIT_FAILURE when we can't parse the thing.