gle: 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/bin/gle - from package: gle

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

On Debian possible default full paths are:

/usr/bin/gle - from package: gle-graphics

You may install the required package with command apt-get install {package}

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