Howto run greater-pre-processing: Required: Python >= 2.2.1 gen2shp >= 0.3.0 txt2dbf >= 1.0.2 dbf2txt >= 0.5.2 GNU Awk >= 3.1.0 GNU sed >= 3.02 GNU textutils (sort, join, cut, paste) >= 2.0 GNU fileutils (rm) >= 4.1 GNU sh-utils (echo) >= 2.0.11 (the programs must be somewhere in your search path) As a first step you have to copy greater-pre-processing.py somewhere into you PATH or extend the PATH to where you have installed the greater-pre-processing package: cp greater-pre-processing.py /some/where/in/your/search/path OR export PATH=$PATH:/some/where/greater-pre-processing Next, set this environment variable that points to where you have installed the greater-pre-processing package: export GREATER_PRE_PROC=/some/where/greater-pre-processing You then are able to execute greater-pre-processing.py in a directory with the pre-defined files for your catchment (you will be given further info on how to use the program).