femon: 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/femon - from package: dvb-apps

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