signaltest: 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/signaltest - from package: rt-tests

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

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