dot2ruby: 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/dot2ruby - from package: ruby-graphviz

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

Error in other languages:
dot2ruby: bevel nie gevind nie
dot2ruby: comandă negăsită
dot2ruby: comando não encontrado
dot2ruby: commande introuvable
dot2ruby: command not found
dot2ruby: käsku ei ole
dot2ruby: không tìm thấy lệnh
dot2ruby: komanda nerasta
dot2ruby: Kommando nicht gefunden.
dot2ruby: kommandot finns inte
dot2ruby: komut yok
dot2ruby: nie znaleziono polecenia
dot2ruby: níor aimsíodh an t-ordú
dot2ruby: no se encontró la orden
dot2ruby: no s'ha trobat l'ordre
dot2ruby: opdracht niet gevonden
dot2ruby: parancs nem található
dot2ruby: perintah tidak ditemukan
dot2ruby: príkaz nenájdený
dot2ruby: příkaz nenalezen
dot2ruby: команда не найдена
dot2ruby: командата не е открита
dot2ruby: 命令找不到
dot2ruby: コマンドが見つかりません