t-prot: command not found

Have You tried accessing the binary with the full path?

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/t-prot - from package: t-prot

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