diff 与patch shell 实例解析

diff的输出格式分为传统格式和统一格式

1)diff的传统格式输出.

suse:~/test/diff_patch # cat before.txt
This is a line to be deleted
This is a line that will be changed
This is a line that will be unchanged

suse:~/test/diff_patch # cat after.txt
s is a line that has been changed
This is a line that will be unchanged
This is a line that has been added

suse:~/test/diff_patch # diff after.txt before.txt
1c1,2
< s is a line that has been changed
---
> This is a line to be deleted
> This is a line that will be changed
3d3
< This is a line that has been added

suse:~/test/diff_patch # diff before.txt after.txt
1,2c1
< This is a line to be deleted
< This is a line that will be changed
---
> s is a line that has been changed
3a3
> This is a line that has been added

注释:

传统格式的输出

1,2c1是指替换第1个文件的第1,2行到第2个文件的第1行,这里的1,2是指第1个文件的第1,2行,c是替换的意思,最后的1是第2个文件的第1行

<号是指第1个文件更改或删除的行

---号是分割两个文件

>号是第2个文件中增加或删除的行

3a3是指将第2个文件的第3行插入到第一个文件的第3行

suse:~/test/diff_patch # diff  before.txt after.txt >patch.txt
suse:~/test/diff_patch # cat patch.txt
1,2c1
< This is a line to be deleted
< This is a line that will be changed
---
> s is a line that has been changed
3a3
> This is a line that has been added
suse:~/test/diff_patch # cat patch.txt |patch before.txt
patching file before.txt
suse:~/test/diff_patch # diff before.txt after.txt
suse:~/test/diff_patch # cmp before.txt after.txt
suse:~/test/diff_patch # patch -R before.txt < patch.txt
patching file before.txt
suse:~/test/diff_patch # diff before.txt after.txt
1,2c1
< This is a line to be deleted
< This is a line that will be changed
---
> s is a line that has been changed
3a3
> This is a line that has been added
suse:~/test/diff_patch # cmp before.txt after.txt
before.txt after.txt differ: char 1, line 1
suse:~/test/diff_patch #

注:-R标记告诉patch在反向上应用区别或者撤销patch.

suse:~/test/diff_patch # diff -u before.txt after.txt |tee patchu.txt
--- before.txt  2012-12-07 10:20:21.536037543 +0800
+++ after.txt   2012-12-07 10:13:52.712264114 +0800
@@ -1,3 +1,3 @@
-This is a line to be deleted
-This is a line that will be changed
+s is a line that has been changed
This is a line that will be unchanged
+This is a line that has been added
suse:~/test/diff_patch # mkdir old new
suse:~/test/diff_patch # echo "This is one. It's unchanged." | tee old/one new/one
This is one. It's unchanged.
suse:~/test/diff_patch # echo "This is two. It will change." > old/two
suse:~/test/diff_patch # echo "This is two. It changed.">new/two
suse:~/test/diff_patch # echo "This is three. It's new" > new/three
suse:~/test/diff_patch # diff -Nur old/ new/ >patchu.txt
suse:~/test/diff_patch # more patchu.txt
diff -Nur old/three new/three
--- old/three   1970-01-01 08:00:00.000000000 +0800
+++ new/three   2012-12-07 10:28:47.854496047 +0800
@@ -0,0 +1 @@
+This is three. It's new
diff -Nur old/two new/two
--- old/two     2012-12-07 10:28:45.884604177 +0800
+++ new/two     2012-12-07 10:28:45.891603793 +0800
@@ -1 +1 @@
-This is two. It will change.
+This is two. It changed.
suse:~/test/diff_patch # patch --dir old< patchu.txt
patching file three
patching file two
suse:~/test/diff_patch # ls -l old/
total 12
-rw-r--r-- 1 root root 29 Dec  7 10:28 one
-rw-r--r-- 1 root root 24 Dec  7 10:30 three
-rw-r--r-- 1 root root 25 Dec  7 10:30 two
suse:~/test/diff_patch # patch --dir old -R < patchu.txt
patching file three
patching file two
suse:~/test/diff_patch # ls -l old/
total 8
-rw-r--r-- 1 root root 29 Dec  7 10:28 one
-rw-r--r-- 1 root root 29 Dec  7 10:30 two
suse:~/test/diff_patch #

注释:

diff -u选项是统一格式输出.

--- before.txt  2009-06-20 05:21:49.000000000 +0800

--- before.txt是指旧文件

+++ after.txt   2009-06-20 04:03:16.000000000 +0800

+++ after.txt是指新文件.

@@ -1,3 +1,3 @@

@@ -1,3是指第1个文件一共有3行,+1,3 @@是指第2个文件一共有3行.

-This is a line to be deleted

-This is a line that will be changed

是被删除的行

+This is a line that has been changed

是增加的行

 This is a line that will be unchanged

没有-号和+号是指该行不变,因为after.txt和before.txt都有这行.

+This is a line that has been added

是增加的行

diff的统一格式比较与输出是按顺序进行的.