GENtle: 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/GENtle - from package: gentle

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

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