g15mpd: 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/g15mpd - from package: g15mpd

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

Error in other languages:
g15mpd: bevel nie gevind nie
g15mpd: comandă negăsită
g15mpd: comando não encontrado
g15mpd: commande introuvable
g15mpd: command not found
g15mpd: käsku ei ole
g15mpd: không tìm thấy lệnh
g15mpd: komanda nerasta
g15mpd: Kommando nicht gefunden.
g15mpd: kommandot finns inte
g15mpd: komut yok
g15mpd: nie znaleziono polecenia
g15mpd: níor aimsíodh an t-ordú
g15mpd: no se encontró la orden
g15mpd: no s'ha trobat l'ordre
g15mpd: opdracht niet gevonden
g15mpd: parancs nem található
g15mpd: perintah tidak ditemukan
g15mpd: príkaz nenájdený
g15mpd: příkaz nenalezen
g15mpd: команда не найдена
g15mpd: командата не е открита
g15mpd: 命令找不到
g15mpd: コマンドが見つかりません