lightspeed: 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/lightspeed - from package: lightspeed

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

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