dpm-ping: 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-ping - from package: dpm

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

On Debian possible default full paths are:

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

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

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