mpd-dynamic: 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/mpd-dynamic - from package: libaudio-mpd-perl

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

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