arb_blend_func_extended-error-at-begin: 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/arb_blend_func_extended-error-at-begin - from package: piglit

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

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