fog-modes: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/fog-modes - from package: piglit

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