gl-1.0-front-invalidate-back: 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-1.0-front-invalidate-back - from package: piglit

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

Error in other languages:
gl-1.0-front-invalidate-back: bevel nie gevind nie
gl-1.0-front-invalidate-back: comandă negăsită
gl-1.0-front-invalidate-back: comando não encontrado
gl-1.0-front-invalidate-back: commande introuvable
gl-1.0-front-invalidate-back: command not found
gl-1.0-front-invalidate-back: käsku ei ole
gl-1.0-front-invalidate-back: không tìm thấy lệnh
gl-1.0-front-invalidate-back: komanda nerasta
gl-1.0-front-invalidate-back: Kommando nicht gefunden.
gl-1.0-front-invalidate-back: kommandot finns inte
gl-1.0-front-invalidate-back: komut yok
gl-1.0-front-invalidate-back: nie znaleziono polecenia
gl-1.0-front-invalidate-back: níor aimsíodh an t-ordú
gl-1.0-front-invalidate-back: no se encontró la orden
gl-1.0-front-invalidate-back: no s'ha trobat l'ordre
gl-1.0-front-invalidate-back: opdracht niet gevonden
gl-1.0-front-invalidate-back: parancs nem található
gl-1.0-front-invalidate-back: perintah tidak ditemukan
gl-1.0-front-invalidate-back: príkaz nenájdený
gl-1.0-front-invalidate-back: příkaz nenalezen
gl-1.0-front-invalidate-back: команда не найдена
gl-1.0-front-invalidate-back: командата не е открита
gl-1.0-front-invalidate-back: 命令找不到
gl-1.0-front-invalidate-back: コマンドが見つかりません