two-sided-lighting: 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/two-sided-lighting - from package: piglit

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

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