musescore: 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/musescore - from package: musescore

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

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