mkvmerge --identify "$mkv"

File '/docs/video/some-file.mkv': container: Matroska
Track ID 0: video (MPEG-4p10/AVC/h.264)
Track ID 1: audio (DTS)
Track ID 2: subtitles (SubRip/SRT)
Track ID 3: subtitles (SubRip/SRT)
Track ID 4: subtitles (SubRip/SRT)
Track ID 5: subtitles (SubRip/SRT)
Track ID 6: subtitles (SubRip/SRT)
Track ID 7: subtitles (SubRip/SRT)
Track ID 8: subtitles (SubRip/SRT)
Track ID 9: subtitles (SubRip/SRT)
Track ID 10: subtitles (SubRip/SRT)
Track ID 11: subtitles (SubRip/SRT)
Track ID 12: subtitles (SubRip/SRT)
Track ID 13: subtitles (SubRip/SRT)
Track ID 14: subtitles (SubRip/SRT)
Track ID 15: subtitles (SubRip/SRT)
Track ID 16: subtitles (SubRip/SRT)

mkvinfo "$mkv" | perl -00 -ne '@tracks=split /^. . . track$/m; foreach (@tracks) {next unless /subtitles/; ($id,$codec,$lang) = /number: .*?: (\d+).*?Codec ID: (\S+)(?:.*?Language: (\w+))?/s; $codec=~s!/!-!g; print "mkvextract tracks \"\$mkv\" $id:$id.$lang.$codec\n";}'

mkvextract tracks "$mkv" 2:2..S_TEXT-UTF8
mkvextract tracks "$mkv" 3:3.ara.S_TEXT-UTF8
mkvextract tracks "$mkv" 4:4.bul.S_TEXT-UTF8
mkvextract tracks "$mkv" 5:5.dan.S_TEXT-UTF8
mkvextract tracks "$mkv" 6:6.dut.S_TEXT-UTF8
mkvextract tracks "$mkv" 7:7.fin.S_TEXT-UTF8
mkvextract tracks "$mkv" 8:8.fre.S_TEXT-UTF8
mkvextract tracks "$mkv" 9:9.ger.S_TEXT-UTF8
mkvextract tracks "$mkv" 10:10.hun.S_TEXT-UTF8
mkvextract tracks "$mkv" 11:11.pol.S_TEXT-UTF8
mkvextract tracks "$mkv" 12:12.por.S_TEXT-UTF8
mkvextract tracks "$mkv" 13:13.rum.S_TEXT-UTF8
mkvextract tracks "$mkv" 14:14.rus.S_TEXT-UTF8
mkvextract tracks "$mkv" 15:15.spa.S_TEXT-UTF8
mkvextract tracks "$mkv" 16:16.swe.S_TEXT-UTF8

mkvextract tracks "$mkv" 2:2..S_TEXT-UTF8

Extracting track 2 with the CodecID 'S_TEXT/UTF8' to the file '2..S_TEXT-UTF8'. Container format: SRT text subtitles
Progress: 100%

• Extract as plain text or xml:

mkvextract chapters -s $mkvfile | tee $mkvile-chapters.txt
mkvextract chapters    $mkvfile | tee $mkvile-chapters.xml

• Add or replace chapters:

mkvpropedit $mkvfile --chapters $mkvile-chapters.txt