fs-discard-exit-2: 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/fs-discard-exit-2 - from package: piglit

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

Error in other languages:
fs-discard-exit-2: bevel nie gevind nie
fs-discard-exit-2: comandă negăsită
fs-discard-exit-2: comando não encontrado
fs-discard-exit-2: commande introuvable
fs-discard-exit-2: command not found
fs-discard-exit-2: käsku ei ole
fs-discard-exit-2: không tìm thấy lệnh
fs-discard-exit-2: komanda nerasta
fs-discard-exit-2: Kommando nicht gefunden.
fs-discard-exit-2: kommandot finns inte
fs-discard-exit-2: komut yok
fs-discard-exit-2: nie znaleziono polecenia
fs-discard-exit-2: níor aimsíodh an t-ordú
fs-discard-exit-2: no se encontró la orden
fs-discard-exit-2: no s'ha trobat l'ordre
fs-discard-exit-2: opdracht niet gevonden
fs-discard-exit-2: parancs nem található
fs-discard-exit-2: perintah tidak ditemukan
fs-discard-exit-2: príkaz nenájdený
fs-discard-exit-2: příkaz nenalezen
fs-discard-exit-2: команда не найдена
fs-discard-exit-2: командата не е открита
fs-discard-exit-2: 命令找不到
fs-discard-exit-2: コマンドが見つかりません