pydoc: 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/pydoc - from package: python

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

On Debian possible default full paths are:

/usr/bin/pydoc - from package: python

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

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