gimptool: 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 CentOS possible default full paths are:

/usr/bin/gimptool - from package: gimp-devel-tools

You may install the required package with command yum install {package}

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