waagent: 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/sbin/waagent - from package: WALinuxAgent

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

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