arb_shader_texture_lod-texgrad: 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_shader_texture_lod-texgrad - from package: piglit

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

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