luajit: 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/luajit - from package: luajit

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

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