refdb-sruserver: 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/refdb-sruserver - from package: refdb-clients

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

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