dpns-ln: 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/dpns-ln - from package: dpm

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

On Debian possible default full paths are:

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

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

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