windowoverlap: 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/windowoverlap - from package: piglit

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

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