whiff: 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/whiff - from package: whiff

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

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