tetrafile: 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/tetrafile - from package: tetraproc

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

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