oggz-diff: 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/oggz-diff - from package: liboggz

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

On Debian possible default full paths are:

/usr/bin/oggz-diff - from package: oggz-tools

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

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