jack_mclk_dump: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/jack_mclk_dump - from package: jack-midi-clock

You may install the required package with command apt-get install {package}

Error in other languages:
jack_mclk_dump: bevel nie gevind nie
jack_mclk_dump: comandă negăsită
jack_mclk_dump: comando não encontrado
jack_mclk_dump: commande introuvable
jack_mclk_dump: command not found
jack_mclk_dump: käsku ei ole
jack_mclk_dump: không tìm thấy lệnh
jack_mclk_dump: komanda nerasta
jack_mclk_dump: Kommando nicht gefunden.
jack_mclk_dump: kommandot finns inte
jack_mclk_dump: komut yok
jack_mclk_dump: nie znaleziono polecenia
jack_mclk_dump: níor aimsíodh an t-ordú
jack_mclk_dump: no se encontró la orden
jack_mclk_dump: no s'ha trobat l'ordre
jack_mclk_dump: opdracht niet gevonden
jack_mclk_dump: parancs nem található
jack_mclk_dump: perintah tidak ditemukan
jack_mclk_dump: príkaz nenájdený
jack_mclk_dump: příkaz nenalezen
jack_mclk_dump: команда не найдена
jack_mclk_dump: командата не е открита
jack_mclk_dump: 命令找不到
jack_mclk_dump: コマンドが見つかりません