mate-screensaver: 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/mate-screensaver - from package: mate-screensaver

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

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