glsl-fs-sampler-numbering: 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-fs-sampler-numbering - from package: piglit

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

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