screenruler: 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/screenruler - from package: screenruler

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

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