relaytest: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/relaytest - from package: dsbltesters

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