irkick: 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/irkick - from package: kdeutils

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

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