ubirsvol: 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/sbin/ubirsvol - from package: mtd-utils

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

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