arb_copy_buffer-targets: 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_copy_buffer-targets - from package: piglit

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

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