spec: 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 CentOS possible default full paths are:

/usr/bin/spec - from package: rubygem-rspec
/usr/lib/ruby/gems/1.8/gems/rspec-1.3.0/bin/spec - from package: rubygem-rspec

You may install the required package with command yum install {package}

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