Reduced Level of Detail
Sometimes the desired resolution of coastlines is not available. A reduced level of detail can be created by using the Douglas-Peucker algorithm, which is implemented in gpsbabel. For this, the coastline file must be converted into a GPS format, which is done by the following script: douglas-peucker.sh.
Usage (example: allow an error of 10 km):
./douglas-peucker.sh 10 < input.gmt > output.gmt