qvality: 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/qvality - from package: percolator

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

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