Merge multiple polygon files

[thewire247]

Issue #268 has been very useful thanks, I managed to get the files merged. Following on from that, how would I merge the polygon files?

[Istador]

See this for the format definition with an example of two areas in one file:
https://wiki.openstreetmap.org/wiki/Osmosis/Polygon_Filter_File_Format

It does say:

Several of these files may be combined to one multi-sectioned file. In this case each section must be separated from its preceding section by an empty line (combined files are used by the programs osmrelpoly and osmassignpoly).

and based on that this should be enough to do the job:

# merge first.poly and second.poly
( cat first.poly && echo "" && cat second.poly ) >merged.poly

# merge first.poly, second.poly and third.poly
( cat first.poly && echo "" && cat second.poly && echo "" && cat third.poly ) >merged.poly

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If that doesn't work (e.g. if osmosis doesn't support it, which I don't know), I'd suggest combining the contents into one section:

# merge first.poly and second.poly
( head -n -1 first.poly && echo 2 && tail -n +3 second.poly ) >merged.poly

# merge first.poly, second.poly and third.poly
( head -n -1 first.poly && echo 2 && ( tail -n +3 second.poly | head -n -1 ) && echo 3 && tail -n +3 third.poly ) >merged.poly