fsynth: 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/fsynth - from package: siggen

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

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