h2synth: 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/h2synth - from package: hydrogen

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

Error in other languages:
h2synth: bevel nie gevind nie
h2synth: comandă negăsită
h2synth: comando não encontrado
h2synth: commande introuvable
h2synth: command not found
h2synth: käsku ei ole
h2synth: không tìm thấy lệnh
h2synth: komanda nerasta
h2synth: Kommando nicht gefunden.
h2synth: kommandot finns inte
h2synth: komut yok
h2synth: nie znaleziono polecenia
h2synth: níor aimsíodh an t-ordú
h2synth: no se encontró la orden
h2synth: no s'ha trobat l'ordre
h2synth: opdracht niet gevonden
h2synth: parancs nem található
h2synth: perintah tidak ditemukan
h2synth: príkaz nenájdený
h2synth: příkaz nenalezen
h2synth: команда не найдена
h2synth: командата не е открита
h2synth: 命令找不到
h2synth: コマンドが見つかりません