grub-editenv: command not found

Have You tried accessing the binary with the full path?

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-editenv - from package: grub-common

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