depth_clamp: 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/depth_clamp - from package: piglit

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

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