baycomusb: 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/sbin/baycomusb - from package: baycomusb

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