xmedcon: 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
/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/xmedcon - from package: xmedcon

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