les: 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 Debian possible default full paths are:

/usr/sbin/les - from package: atm-tools

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

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