This is the approach that I use except that I generate a Makefile which has: - a target to split the input into chunks - targets to sort each of the split

This is the approach that I use except that I generate a Makefile which has: - a target to split the input into chunks - targets to sort each of the split chunks - a target to merge the sorted chunks using "sort -m" Then, if you are using GNU make, it's just a matter of using the -j flag to control how many chunks are sorted in parallel.