rushwho: 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/rushwho - from package: rush

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

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