multiruby: 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/multiruby - from package: ruby-zentest

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

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