xfce4-kiosk-query: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/sbin/xfce4-kiosk-query - from package: libxfce4util

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

On Debian possible default full paths are:

/usr/sbin/xfce4-kiosk-query - from package: libxfce4util-bin

You may install the required package with command apt-get install {package}
Error in other languages:
xfce4-kiosk-query: bevel nie gevind nie
xfce4-kiosk-query: comandă negăsită
xfce4-kiosk-query: comando não encontrado
xfce4-kiosk-query: commande introuvable
xfce4-kiosk-query: command not found
xfce4-kiosk-query: käsku ei ole
xfce4-kiosk-query: không tìm thấy lệnh
xfce4-kiosk-query: komanda nerasta
xfce4-kiosk-query: Kommando nicht gefunden.
xfce4-kiosk-query: kommandot finns inte
xfce4-kiosk-query: komut yok
xfce4-kiosk-query: nie znaleziono polecenia
xfce4-kiosk-query: níor aimsíodh an t-ordú
xfce4-kiosk-query: no se encontró la orden
xfce4-kiosk-query: no s'ha trobat l'ordre
xfce4-kiosk-query: opdracht niet gevonden
xfce4-kiosk-query: parancs nem található
xfce4-kiosk-query: perintah tidak ditemukan
xfce4-kiosk-query: príkaz nenájdený
xfce4-kiosk-query: příkaz nenalezen
xfce4-kiosk-query: команда не найдена
xfce4-kiosk-query: командата не е открита
xfce4-kiosk-query: 命令找不到
xfce4-kiosk-query: コマンドが見つかりません