Patching multiplier files

dry run (check first)

patch -p1 --dry-run -i 323cc165b663a078c50da10ca9d79c48feddd4a4.patch

patch multiplier files

patch -p1 -i 323cc165b663a078c50da10ca9d79c48feddd4a4.patch

patch single file

patch foo.c < patch.diff

Undo patch

patch -R < /path/to/file

more sources
http://www.cyberciti.biz/faq/appy-patch-file-using-patch-command/