tyalpha: 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/bin/tyalpha - from package: terminology

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

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