biff: 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/biff - from package: biff

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

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