grlearn: 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:

/sbin/grlearn - from package: gradm2

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