rsuplnk: 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/rsuplnk - from package: ax25-tools

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

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