glean: 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/glean - from package: piglit

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

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