linux 打補丁 2原理

1.創建目錄 demo

cd demo

 

有bug文件a.txt：

當前目錄為demo

mkdir -p  old/a/p

vi   old/a/p/foo.txt

old_line_1

old_line_2

 

bug 修復后的foo.txt：

當前目錄為demo

mkdir -p  new/a/p

vi   new/a/p/foo.txt

new_line_1

new_line_2

 

補丁產生:

當前目錄為demo

LC_ALL=C TZ=UTC0 diff -Naur old new > foo.patch

 

補丁內容：
當前目錄為demo

[root@monitor demo]# cat foo.patch
diff -Naur old/a/b/foo.txt new/a/b/foo.txt
--- old/a/b/foo.txt     2016-05-26 06:57:56.999206666 +0000
+++ new/a/b/foo.txt     2016-05-26 06:59:03.160497528 +0000
@@ -1,2 +1,2 @@
-old_line_1
-old_line_2
+new_line_1
+new_line_2

模擬打補丁：(補丁針對 old/a/b.foo.txt文件打補丁）
當前目錄demo

[root@monitor demo]# patch -p0 <foo.patch
 patching file old/a/b/foo.txt

當前目錄demo

[root@monitor demo]# mkdir xx
[root@monitor demo]# cp foo.patch xx
[root@monitor demo]# patch -p0 < xx/foo.patch
 patching file old/a/b/foo.txt

 

cd xx

當前目錄為demo/xx

[root@monitor xx]# patch -p0 < foo.patch 

can't find file to patch at input line 4
Perhaps you used the wrong -p or --strip option?
The text leading up to this was:
--------------------------
|diff -Naur old/a/b/foo.txt new/a/b/foo.txt
|--- old/a/b/foo.txt 2016-05-26 06:57:56.999206666 +0000
|+++ new/a/b/foo.txt 2016-05-26 06:59:03.160497528 +0000

說明在當前目錄不能找到  old/a/b/foo.txt (在demo/xx目錄下找到文件與目錄去補丁

P0:你當前的目錄位置,去找old/a/b/foo.txt

p1:你當前目錄位置去找a/b/foo.txt,p1會掉old/,到當前目錄找a/b/foo.txt


p2:你當前目錄位置去找a/b/foo.txt,p2會掉old/a,到當前目錄找b/foo.txt

p3:你當前目錄位置去找a/b/foo.txt,p3會掉old/a/b,到當前目錄找foo.txt

結論：決定補丁如何補:你的補丁所在的目錄（你該把補丁放在那里)
     P(N)決定去查找要補丁的文件路徑,不同的N,會掉某部分路徑后,再在當前目錄,找已除掉后路徑,找文件去補丁
     P(N)與當前目錄關系很大,與補丁在那里沒有關系

    patch -d xx  P(N) 〈 XX  可以命令行上指定 工作目錄