glx-fbconfig-sanity: 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-fbconfig-sanity - from package: piglit

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

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