ruby-spork: 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/ruby-spork - from package: spork

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

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