dpns-rm: command not found

Have You tried accessing the binary with the full path?

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/dpns-rm - from package: dpm

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

On Debian possible default full paths are:

/usr/bin/dpns-rm - from package: dpm

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