ppdpo: 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/ppdpo - from package: cups

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

On Debian possible default full paths are:

/usr/bin/ppdpo - from package: cups-ppdc

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

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