cupstestppd: 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/cupstestppd - from package: cups

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

On Debian possible default full paths are:

/usr/bin/cupstestppd - from package: cups-client

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

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