vao-01: 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/vao-01 - from package: piglit

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

Error in other languages:
vao-01: bevel nie gevind nie
vao-01: comandă negăsită
vao-01: comando não encontrado
vao-01: commande introuvable
vao-01: command not found
vao-01: käsku ei ole
vao-01: không tìm thấy lệnh
vao-01: komanda nerasta
vao-01: Kommando nicht gefunden.
vao-01: kommandot finns inte
vao-01: komut yok
vao-01: nie znaleziono polecenia
vao-01: níor aimsíodh an t-ordú
vao-01: no se encontró la orden
vao-01: no s'ha trobat l'ordre
vao-01: opdracht niet gevonden
vao-01: parancs nem található
vao-01: perintah tidak ditemukan
vao-01: príkaz nenájdený
vao-01: příkaz nenalezen
vao-01: команда не найдена
vao-01: командата не е открита
vao-01: 命令找不到
vao-01: コマンドが見つかりません