kdiamond: 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/kdiamond - from package: kdegames

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

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