ext_transform_feedback-separate: 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/ext_transform_feedback-separate - from package: piglit

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

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