auth2db: 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/auth2db - from package: auth2db

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

Error in other languages:
auth2db: bevel nie gevind nie
auth2db: comandă negăsită
auth2db: comando não encontrado
auth2db: commande introuvable
auth2db: command not found
auth2db: käsku ei ole
auth2db: không tìm thấy lệnh
auth2db: komanda nerasta
auth2db: Kommando nicht gefunden.
auth2db: kommandot finns inte
auth2db: komut yok
auth2db: nie znaleziono polecenia
auth2db: níor aimsíodh an t-ordú
auth2db: no se encontró la orden
auth2db: no s'ha trobat l'ordre
auth2db: opdracht niet gevonden
auth2db: parancs nem található
auth2db: perintah tidak ditemukan
auth2db: príkaz nenájdený
auth2db: příkaz nenalezen
auth2db: команда не найдена
auth2db: командата не е открита
auth2db: 命令找不到
auth2db: コマンドが見つかりません