mpcdec: 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/mpcdec - from package: musepack-tools

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

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