pdldoc: 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/pdldoc - from package: perl-PDL

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

On Debian possible default full paths are:

/usr/bin/pdldoc - from package: pdl

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

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