instanced_arrays: 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/instanced_arrays - from package: piglit

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

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