Dealing with large tabular datasets often requires extensive preprocessing. This preprocessing happens only once, so that loading and indexing the data in a database or triple store may be an overkill. In this paper, we present an approach that allows preprocessing large tabular data in Datalog – without indexing the data. The Datalog query is translated to Unix Bash and can be executed in a shell. Our experiments show that, for the use case of data preprocessing, our approach is competitive with state-of-the-art systems in terms of scalability and speed, while at the same time requiring only a Bash shell on a Unix system.