copypixels-sync: 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/lib64/piglit/bin/copypixels-sync - from package: piglit

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

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