iauth: 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/sbin/iauth - from package: ircd-irc2

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

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