patdiff: 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/patdiff - from package: dist

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

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