lnptest: 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/lnptest - from package: lnpd

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

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