sso-simple: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/sso-simple - from package: piglit

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