ttylinkd: 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/ttylinkd - from package: ax25-tools

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

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