diff2patches: 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/diff2patches - from package: devscripts

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

Error in other languages:
diff2patches: bevel nie gevind nie
diff2patches: comandă negăsită
diff2patches: comando não encontrado
diff2patches: commande introuvable
diff2patches: command not found
diff2patches: käsku ei ole
diff2patches: không tìm thấy lệnh
diff2patches: komanda nerasta
diff2patches: Kommando nicht gefunden.
diff2patches: kommandot finns inte
diff2patches: komut yok
diff2patches: nie znaleziono polecenia
diff2patches: níor aimsíodh an t-ordú
diff2patches: no se encontró la orden
diff2patches: no s'ha trobat l'ordre
diff2patches: opdracht niet gevonden
diff2patches: parancs nem található
diff2patches: perintah tidak ditemukan
diff2patches: príkaz nenájdený
diff2patches: příkaz nenalezen
diff2patches: команда не найдена
diff2patches: командата не е открита
diff2patches: 命令找不到
diff2patches: コマンドが見つかりません