piglit-summary: 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/bin/piglit-summary - from package: piglit

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

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