9mount: 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/9mount - from package: 9mount

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

Error in other languages:
9mount: bevel nie gevind nie
9mount: comandă negăsită
9mount: comando não encontrado
9mount: commande introuvable
9mount: command not found
9mount: käsku ei ole
9mount: không tìm thấy lệnh
9mount: komanda nerasta
9mount: Kommando nicht gefunden.
9mount: kommandot finns inte
9mount: komut yok
9mount: nie znaleziono polecenia
9mount: níor aimsíodh an t-ordú
9mount: no se encontró la orden
9mount: no s'ha trobat l'ordre
9mount: opdracht niet gevonden
9mount: parancs nem található
9mount: perintah tidak ditemukan
9mount: príkaz nenájdený
9mount: příkaz nenalezen
9mount: команда не найдена
9mount: командата не е открита
9mount: 命令找不到
9mount: コマンドが見つかりません