Patch

How to use diff

The basic use of diff is

diff -u original.txt modified.txt > file.patch

If you want to use diff against two source tree, the command is

diff -rupN original modified > program.patch

To apply the patch, change into the same directory as the unmodified file and execute

patch < file.patch

This is how to apply patch to an entire directory

patch -p0 < program.patch

Patch applied can be simply removed by adding the -R switch

patch -p0 -R < program.patch
patch -R < file.patch