theseus: 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/theseus - from package: theseus

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

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