lxsession-xsettings: 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-xsettings - from package: lxsession

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

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