thuban: 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/thuban - from package: thuban

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

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