mopidy: command not found

Have You tried accessing the binary with the full path?

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/mopidy - from package: mopidy

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