update-efi-nvram-boot-entry: 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/update-efi-nvram-boot-entry - from package: clonezilla

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

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