blinkenlights: 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/blinkenlights - from package: dnssec-tools

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

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