kblocks: 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/kblocks - from package: kdegames

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

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