kruler: 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/kruler - from package: kdegraphics

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

On Debian possible default full paths are:

/usr/bin/kruler - from package: kruler

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

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