Examples:
mkvmerge -o out.mkv [ in1.avi in2.avi in3.avi ]
Of course shells may treat [ and ] special, so the user should escape
them:
mkvmerge -o out.mkv '[' in1.avi in2.avi in3.avi ']'
The nice thing is to use the shell's file name expansion for appending:
mkvmerge -o out.mkv '[' in*.avi ']'
