isotptun: 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/isotptun - from package: can-utils

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

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