fluidsynth: 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/fluidsynth - from package: fluidsynth

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

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