qpdldecode: 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/qpdldecode - from package: printer-driver-foo2zjs

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

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