kdump: 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:

/sbin/kdump - from package: kexec-tools

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

On Debian possible default full paths are:

/sbin/kdump - from package: kexec-tools

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

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