x-grass: 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/x-grass - from package: grass-core

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

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