arb-provoking-vertex-initial: 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/arb-provoking-vertex-initial - from package: piglit

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

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