xeno-config: 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/xeno-config - from package: libxenomai-dev

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

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