glsl-arb-fragment-coord-conventions: 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/glsl-arb-fragment-coord-conventions - from package: piglit

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

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