glx-buffer-age: 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/glx-buffer-age - from package: piglit

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

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