gnarwl: 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/gnarwl - from package: gnarwl

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

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