glsl-explicit-location-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/glsl-explicit-location-01 - from package: piglit

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

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