xsettings-kde: 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/xsettings-kde - from package: xsettings-kde

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

On Debian possible default full paths are:

/usr/bin/xsettings-kde - from package: xsettings-kde

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

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