gimp-console-2.8: 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/gimp-console-2.8 - from package: gimp

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

Error in other languages:
gimp-console-2.8: bevel nie gevind nie
gimp-console-2.8: comandă negăsită
gimp-console-2.8: comando não encontrado
gimp-console-2.8: commande introuvable
gimp-console-2.8: command not found
gimp-console-2.8: käsku ei ole
gimp-console-2.8: không tìm thấy lệnh
gimp-console-2.8: komanda nerasta
gimp-console-2.8: Kommando nicht gefunden.
gimp-console-2.8: kommandot finns inte
gimp-console-2.8: komut yok
gimp-console-2.8: nie znaleziono polecenia
gimp-console-2.8: níor aimsíodh an t-ordú
gimp-console-2.8: no se encontró la orden
gimp-console-2.8: no s'ha trobat l'ordre
gimp-console-2.8: opdracht niet gevonden
gimp-console-2.8: parancs nem található
gimp-console-2.8: perintah tidak ditemukan
gimp-console-2.8: príkaz nenájdený
gimp-console-2.8: příkaz nenalezen
gimp-console-2.8: команда не найдена
gimp-console-2.8: командата не е открита
gimp-console-2.8: 命令找不到
gimp-console-2.8: コマンドが見つかりません