openstack.rb: command not found

Have You tried accessing the binary with the full path?

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/lib/ruby/vendor_ruby/fog/bin/openstack.rb - from package: ruby-fog

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