比较文件将结果保存到patch文件：diff -u test1.txt test2.txt > patchfile
test1.txt应用patch文件，并备份(test1.txt.orig)：patch -b test1.txt patchfile
升级成功后test1.txt和test2.txt是一样的：diff test1.txt test2.txt
将test1.txt回退到旧版本：patch -R test1.txt patchfile
回退成功后test1.txt和test1.txt.orig是一样的：diff test1.txt test1.txt.orig