To install mkvmerge

$ sudo apt install mkvtoolnix mkvtoolnix-gui

To merge multiple .mkv files

$ mkvmerge -o output.mkv input1.mkv +input2.mkv +input3.mkv

To increase verbosity

$ mkvmerge -o --verbose output.mkv input1.mkv +input2.mkv +input3.mkv

To suppress status output

$ mkvmerge -o -q output.mkv input1.mkv +input2.mkv +input3.mkv

To get help info

$ mkvmerge --help

regards,

T.Dhanasekar