canfdtest: 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/canfdtest - from package: can-utils

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

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