Best way to combine three 7GB mkv files

[jbrown96]

I have a movie split into three mkv video files. They all use the same codec, resolutions, etc. I am just looking for a way to combine all three. Suggestions on program?

[FakeOutdoorsman]

You could try MP4Box which is part of the gpac package:
MP4Box -cat file1.mp4 -cat file2.mp4 -cat file3.mp4 output.mp4
No quality loss because there is no re-encoding.

[FakeOutdoorsman]

I assumed MP4Box would work with h264/aac mkv files, but it didn't work for me. Might have better luck with mkvmerge from the mkvtoolnix package (mkvtoolnix-gui for GUI), but I have no experience with it:
mkvmerge -o output.mkv file1.mkv file2.mkv file3.mkv