old_file.txt と new_file.txt の差分から mysterious.patch を作成するコマンドはどれですか？
old_file.txt
new_file.txt
mysterious.patch
patch -p0 old_file.txt new_file.txt > mysterious.patch
diff -uN old_file.txt new_file.txt > mysterious.patch
diff -uN old_file.txt new_file.txt < mysterious.patch
diff -uN new_file.txt old_file.txt > mysterious.patch