lv2_simple_jack_host: 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/lv2_simple_jack_host - from package: slv2-jack

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

Error in other languages:
lv2_simple_jack_host: bevel nie gevind nie
lv2_simple_jack_host: comandă negăsită
lv2_simple_jack_host: comando não encontrado
lv2_simple_jack_host: commande introuvable
lv2_simple_jack_host: command not found
lv2_simple_jack_host: käsku ei ole
lv2_simple_jack_host: không tìm thấy lệnh
lv2_simple_jack_host: komanda nerasta
lv2_simple_jack_host: Kommando nicht gefunden.
lv2_simple_jack_host: kommandot finns inte
lv2_simple_jack_host: komut yok
lv2_simple_jack_host: nie znaleziono polecenia
lv2_simple_jack_host: níor aimsíodh an t-ordú
lv2_simple_jack_host: no se encontró la orden
lv2_simple_jack_host: no s'ha trobat l'ordre
lv2_simple_jack_host: opdracht niet gevonden
lv2_simple_jack_host: parancs nem található
lv2_simple_jack_host: perintah tidak ditemukan
lv2_simple_jack_host: príkaz nenájdený
lv2_simple_jack_host: příkaz nenalezen
lv2_simple_jack_host: команда не найдена
lv2_simple_jack_host: командата не е открита
lv2_simple_jack_host: 命令找不到
lv2_simple_jack_host: コマンドが見つかりません