sidplay2: 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/sidplay2 - from package: sidplay

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

Error in other languages:
sidplay2: bevel nie gevind nie
sidplay2: comandă negăsită
sidplay2: comando não encontrado
sidplay2: commande introuvable
sidplay2: command not found
sidplay2: käsku ei ole
sidplay2: không tìm thấy lệnh
sidplay2: komanda nerasta
sidplay2: Kommando nicht gefunden.
sidplay2: kommandot finns inte
sidplay2: komut yok
sidplay2: nie znaleziono polecenia
sidplay2: níor aimsíodh an t-ordú
sidplay2: no se encontró la orden
sidplay2: no s'ha trobat l'ordre
sidplay2: opdracht niet gevonden
sidplay2: parancs nem található
sidplay2: perintah tidak ditemukan
sidplay2: príkaz nenájdený
sidplay2: příkaz nenalezen
sidplay2: команда не найдена
sidplay2: командата не е открита
sidplay2: 命令找不到
sidplay2: コマンドが見つかりません