Generate Patch

diff -u version1 version2 > change.patch

Apply patch

patch -p1 version1 < change.patch

will change version1 to be the same with version2

if run once more

patch -p1 version1<change.patch
Reversed (or previously applied) patch detected! Assume -R? [n] y

will reverse version1 to the original version1

patch -p1 version2<change.patch
Reversed (or previously applied) patch detected! Assume -R? [n] y

will change version2 to be the same with version1

if run once more

patch -p1 version2<change.patch

will reverse version2 to the original version2

if your need patch fold

like linux kernel patch

diff -Nur fold1 fold2 > change.path