cupsreject: 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/sbin/cupsreject - from package: cups

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

On Debian possible default full paths are:

/usr/sbin/cupsreject - from package: cups-client

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

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