PWTK is a Tcl scripting interface to PWscf set of programs contained in the Quantum ESPRESSO distribution. It aims at providing a flexible and productive framework.
PWTK allows to easily automate large number of calculations and to glue together different computational tasks, where output data of preceding calculations serve as input for subsequent calculations.
To get a first idea of what the PWTK is, see this presentation: (PDF, 1.8M)
Click here (HTML).