irkerhook-debian: 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 Debian possible default full paths are:

/usr/bin/irkerhook-debian - from package: irker

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

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