ez-ipupdate: 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/ez-ipupdate - from package: ez-ipupdate

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

On Debian possible default full paths are:

/usr/sbin/ez-ipupdate - from package: ez-ipupdate

You may install the required package with command apt-get install {package}

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