grub-script-check: 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/grub-script-check - from package: grub-common

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

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