pdb2mdb: 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/pdb2mdb - from package: mono-core

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

On Debian possible default full paths are:

/usr/bin/pdb2mdb - from package: mono-devel

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

Error in other languages:
pdb2mdb: bevel nie gevind nie
pdb2mdb: comandă negăsită
pdb2mdb: comando não encontrado
pdb2mdb: commande introuvable
pdb2mdb: command not found
pdb2mdb: käsku ei ole
pdb2mdb: không tìm thấy lệnh
pdb2mdb: komanda nerasta
pdb2mdb: Kommando nicht gefunden.
pdb2mdb: kommandot finns inte
pdb2mdb: komut yok
pdb2mdb: nie znaleziono polecenia
pdb2mdb: níor aimsíodh an t-ordú
pdb2mdb: no se encontró la orden
pdb2mdb: no s'ha trobat l'ordre
pdb2mdb: opdracht niet gevonden
pdb2mdb: parancs nem található
pdb2mdb: perintah tidak ditemukan
pdb2mdb: príkaz nenájdený
pdb2mdb: příkaz nenalezen
pdb2mdb: команда не найдена
pdb2mdb: командата не е открита
pdb2mdb: 命令找不到
pdb2mdb: コマンドが見つかりません