sso-user-varying-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/sso-user-varying-01 - from package: piglit

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

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