gl-3.2-clear-no-buffers: 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/gl-3.2-clear-no-buffers - from package: piglit

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

Error in other languages:
gl-3.2-clear-no-buffers: bevel nie gevind nie
gl-3.2-clear-no-buffers: comandă negăsită
gl-3.2-clear-no-buffers: comando não encontrado
gl-3.2-clear-no-buffers: commande introuvable
gl-3.2-clear-no-buffers: command not found
gl-3.2-clear-no-buffers: käsku ei ole
gl-3.2-clear-no-buffers: không tìm thấy lệnh
gl-3.2-clear-no-buffers: komanda nerasta
gl-3.2-clear-no-buffers: Kommando nicht gefunden.
gl-3.2-clear-no-buffers: kommandot finns inte
gl-3.2-clear-no-buffers: komut yok
gl-3.2-clear-no-buffers: nie znaleziono polecenia
gl-3.2-clear-no-buffers: níor aimsíodh an t-ordú
gl-3.2-clear-no-buffers: no se encontró la orden
gl-3.2-clear-no-buffers: no s'ha trobat l'ordre
gl-3.2-clear-no-buffers: opdracht niet gevonden
gl-3.2-clear-no-buffers: parancs nem található
gl-3.2-clear-no-buffers: perintah tidak ditemukan
gl-3.2-clear-no-buffers: príkaz nenájdený
gl-3.2-clear-no-buffers: příkaz nenalezen
gl-3.2-clear-no-buffers: команда не найдена
gl-3.2-clear-no-buffers: командата не е открита
gl-3.2-clear-no-buffers: 命令找不到
gl-3.2-clear-no-buffers: コマンドが見つかりません