dpm-drain: 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/dpm-drain - from package: dpm

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

On Debian possible default full paths are:

/usr/bin/dpm-drain - from package: dpm

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

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