amsynth: 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/amsynth - from package: amsynth

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

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