lxsession: 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/bin/lxsession - from package: lxsession

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

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