rsdwnlnk: 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/sbin/rsdwnlnk - from package: ax25-tools

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

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