pdb: 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 Debian possible default full paths are:

/usr/bin/pdb - from package: python

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

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