early-z: 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/early-z - from package: piglit

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

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