rup: 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 CentOS possible default full paths are:

/usr/bin/rup - from package: rusers

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/rup - from package: rstat-client

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

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