scsynth: 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/scsynth - from package: supercollider-server

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

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