ext_framebuffer_multisample-enable-flag: 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_framebuffer_multisample-enable-flag - from package: piglit

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

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