euca-associate-dhcp-options: 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/euca-associate-dhcp-options - from package: euca2ools

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

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