puzzle-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/puzzle-diff - from package: libpuzzle

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

On Debian possible default full paths are:

/usr/bin/puzzle-diff - from package: libpuzzle-bin

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

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