kdm: 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/kdm - from package: kdm

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

On Debian possible default full paths are:

/usr/bin/kdm - from package: kdm

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

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