mdb-ver: 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/mdb-ver - from package: mdbtools

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

On Debian possible default full paths are:

/usr/bin/mdb-ver - from package: mdbtools

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

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