arb_viewport_array-render-viewport: 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_viewport_array-render-viewport - from package: piglit

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

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