mdump3: 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/mdump3 - from package: med-tools

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

On Debian possible default full paths are:

/usr/bin/mdump3 - from package: libmed-tools

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

Error in other languages:
mdump3: bevel nie gevind nie
mdump3: comandă negăsită
mdump3: comando não encontrado
mdump3: commande introuvable
mdump3: command not found
mdump3: käsku ei ole
mdump3: không tìm thấy lệnh
mdump3: komanda nerasta
mdump3: Kommando nicht gefunden.
mdump3: kommandot finns inte
mdump3: komut yok
mdump3: nie znaleziono polecenia
mdump3: níor aimsíodh an t-ordú
mdump3: no se encontró la orden
mdump3: no s'ha trobat l'ordre
mdump3: opdracht niet gevonden
mdump3: parancs nem található
mdump3: perintah tidak ditemukan
mdump3: príkaz nenájdený
mdump3: příkaz nenalezen
mdump3: команда не найдена
mdump3: командата не е открита
mdump3: 命令找不到
mdump3: コマンドが見つかりません