xdg-settings: 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/xdg-settings - from package: xdg-utils

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

On Debian possible default full paths are:

/usr/bin/xdg-settings - from package: xdg-utils

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

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