seyon: 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/seyon - from package: seyon

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

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