emacs-23.1-nox: 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/emacs-23.1-nox - from package: emacs-nox

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

Error in other languages:
emacs-23.1-nox: bevel nie gevind nie
emacs-23.1-nox: comandă negăsită
emacs-23.1-nox: comando não encontrado
emacs-23.1-nox: commande introuvable
emacs-23.1-nox: command not found
emacs-23.1-nox: käsku ei ole
emacs-23.1-nox: không tìm thấy lệnh
emacs-23.1-nox: komanda nerasta
emacs-23.1-nox: Kommando nicht gefunden.
emacs-23.1-nox: kommandot finns inte
emacs-23.1-nox: komut yok
emacs-23.1-nox: nie znaleziono polecenia
emacs-23.1-nox: níor aimsíodh an t-ordú
emacs-23.1-nox: no se encontró la orden
emacs-23.1-nox: no s'ha trobat l'ordre
emacs-23.1-nox: opdracht niet gevonden
emacs-23.1-nox: parancs nem található
emacs-23.1-nox: perintah tidak ditemukan
emacs-23.1-nox: príkaz nenájdený
emacs-23.1-nox: příkaz nenalezen
emacs-23.1-nox: команда не найдена
emacs-23.1-nox: командата не е открита
emacs-23.1-nox: 命令找不到
emacs-23.1-nox: コマンドが見つかりません