I always keep forgetting how to do this properly, so this is the case:
mkvmerge -o "outputfile.mkv" inputfile1.mkv + inputfile2.mkv
How to merge video files under Linux
I generally dislike when movies are divided in two or more parts, although it’s just one more click to load 2nd or 3rd file, I prefer joining them together. Up until recently I was using avimerge tool fromtranscode package to do all of my merging, just because it was so simple to do with:
avimerge -i inputfile1.avi inputfile2.avi -o outputfile.avi