xbiff: 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 CentOS possible default full paths are:

/usr/bin/xbiff - from package: xorg-x11-apps

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/xbiff - from package: x11-apps

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

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