原始碼 diff and patch

開發專案的時候常常需要協同合作，可以不用把所有原始碼寄給對方，只把寄自己修改過的內容就可以。下面是一個操作實例，修正內容我們可以用diff 指令產生，而對方用 patch 把你修正的內容加入原始碼。

1. 自己開發的程式內容

檔案列表如下

test/Makefile

test/test.c

test.c 內容如下

#include <stdio.h>

int main(int argc, char **argv)
{
    printf("Hello World!\n");
    return 0;
}

2. 打包寄給協同開發者

將 test 整個打包

tar czvf test.tgz test/

3. 協同開發者開始更改

tar zxvf test.tgz

cp test test1 -rf

檔案列表如下

test1/Makefile

test1/test.c

test1/README

README 內容如下

Hello! It's README file.

修改 test.c 內容如下

#include <stdio.h>

int main(int argc, char **argv)
{
        printf("Hello World!\n");
        printf("Hello c program\n");
        return 0;
}

4. 產生 patch 檔

語法如下

diff -Naur [from-file] [to-file] > [YourFileName.patch]

-N    In  directory comparison, if a file is found in only one directory, treat it as present but empty in the other directory.

-a    Treat  all  files as text and compare them line-by-line, even if they do not seem to be text.

-u    Use the unified output format.

-r    When comparing directories, recursively compare any subdirectories found.

依我們的情況下指令如下，產生 test.patch 檔

diff -Naur test test1 > test.patch

test.patch 內容如下

diff -Naur test/README test1/README
--- test/README 1970-01-01 08:00:00.000000000 +0800
+++ test1/README        2010-06-09 16:01:32.000000000 +0800
@@ -0,0 +1 @@
+Hello! It's README file.
diff -Naur test/test.c test1/test.c
--- test/test.c 2010-06-09 16:01:06.000000000 +0800
+++ test1/test.c        2010-06-09 16:00:25.000000000 +0800
@@ -3,5 +3,6 @@
 int main(int argc, char **argv)
 {
        printf("Hello World!\n");
+       printf("Hello c program\n");
        return 0;
 }

將 test.patch 寄回給原開發者

5. 開始 patch

patch 語法如下

patch -p0 < [patchfile]

將之前的test.tgz解開

tar zxvf test.tgz

patch -p0 < test.patch

[~]# patch -p0 < test.patch
patching file test/README
patching file test/test.c

6. 移除 patch 內容

再作一次patch即可，程式會詢問你

或者也可以增加參數 -R 來回覆修改

patch -p0 < test.patch

或是

patch -R -p0 < test.patch

[~]# patch -p0 < test.patch
The next patch would create the file test/README,
which already exists!  Assume -R? [n] y
patching file test/README
patching file test/test.c
Reversed (or previously applied) patch detected!  Assume -R? [n] y