razor-lightdm-greeter: 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/razor-lightdm-greeter - from package: razorqt-lightdm-greeter

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

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