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《Linux diff与patch的深入分析》

技术2022-05-11  0

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.############################################cat before.txt输出:This is a line to be deletedThis is a line that will be changedThis is a line that will be unchangedcat after.txt输出: This is a line that has been changedThis is a line that will be unchangedThis is a line that has been added############################################diff before.txt after.txt 输 出:1,2c1< This is a line to be deleted< This is a line that will be changed---> This is a line that has been changed3a3> 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2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行也就是说第1个文件的:< This is a line to be deleted< This is a line that will be changed被替换成第2个文件的:> This is a line that has been changed由于第1个文件的第3行和第2个文件的第2行一致,所以不做修改.由于第2个文件的第3行是第1个文件所不具有的,所以在第1个文件的最后一行增加:> This is a line that has been added2)patch命令的应用用diff的传统格式输出:#################################diff before.txt after.txt >mypatch.txt#################################用patch修补before.txt文件,使before.txt和after.txt一致.#################################cat mypatch.txt |patch before.txt 输出:patching file before.txt#################################比较两个文件,现在是一致的了.#################################cmp before.txt after.txt #################################用patch命令恢复before.txt.#################################patch -R before.txt <mypatch.txt输出:patching file before.txt#################################注:-R标记告诉patch在反向上应用区别或者撤销patch.再比较两个文件,现在不一致了.#################################cmp before.txt after.txt 输出:before.txt after.txt differ: byte 17, line 1#################################3)diff的统一格式输出.#################################diff -u before.txt after.txt |tee mypatch.diff输出:--- before.txt  2009-06-20 05:21:49.000000000 +0800+++ after.txt   2009-06-20 04:03:16.000000000 +0800@@ -1,3 +1,3 @@-This is a line to be deleted-This is a line that will be changed+This is a line that has been changed This is a line that will be unchanged+This is a line that has been added#################################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.4)diff命令在目录中的应用.新建old和new目录,old目录包含了初始内容,new目录包含文件的最新版本.##########################################mkdir old newecho "This is one. It's unchanged." | tee old/one new/oneecho "This is two. It will change." > old/twoecho "This is two. It changed.">new/twoecho "This is three. It's new" > new/three##########################################创建修补文件##########################################diff -Nur old/ new/ >mypatch.diff##########################################注:-r选项按照文件目录递归创建修补文件.-u还是统一模式-N是指当diff遇到一个只存在于两个树中的一个树中的文件时,默认情况下跳过文件并且打印一个警告到stderr.这个行为可以通过-N选项来更改,这也导致了diff认为丢失的文件实际上是存在的,但它是空的.采用这种方式,一个修补文件可以包括已经创建的文件.然后应用修补程序创建新的文件.##########################################more mypatch.diff 输出:diff -Nur old/three new/three--- old/three   1970-01-01 08:00:00.000000000 +0800+++ new/three   2009-06-20 06:55:34.000000000 +0800@@ -0,0 +1 @@+This is three. It's newdiff -Nur old/two new/two--- old/two     2009-06-20 06:55:08.000000000 +0800+++ new/two     2009-06-20 06:55:21.000000000 +0800@@ -1 +1 @@-This is two. It will change.+This is two. It changed.##########################################注释:diff -Nur old/three new/three是指下面比较old/three new/three两个文件.因为没有old/three文件,所以在old/three中增加+This is three. It's newdiff -Nur old/two new/two是指下面比较old/two new/two两个文件因为old/two与new/two的第3行不一致,所以删除This is two. It will change.增加This is two. It changed.打补丁到old目录,新建old/three以及更改old/two##########################################patch --dir old< mypatch.diffls -l     old/输出:one    three  two ##########################################恢复old目录的内容,包括删除old/three,以及恢复old/two文件##########################################patch --dir old -R <mypatch.diff输出:ls -l old/one  two  ##########################################5)检查和合并更改用vim突出显示单个字符的更改来表示区别.##########################################vim -d after.txt before.txt##########################################用gui工具gvimdiff来显示两个文件.##########################################gvimdiff after.txt before.txt##########################################新建文件orig.c##########################################vi orig.c void foo(void){    printf("This will be changed by me. /n");    printf("This will be unchanged,/n");    printf("This will be changed by you./n");}##########################################复制文件orig.c到me.c,更改第4行为printf("This was changed by me. /n");##########################################vi me.c void foo(void){    printf("This was changed by me. /n");    printf("This will be unchanged,/n");    printf("This will be changed by you./n");}##########################################复制文件orig.c到you.c,更改第7行为printf("This was changed by you./n");##########################################vi you.c void foo(void){    printf("This will be changed by me. /n");    printf("This will be unchanged,/n");    printf("This was changed by you./n");}##########################################版本工具如cvs,subversion使用GNU合并工具称为diff3.##########################################diff3 me.c orig.c you.c 输出:====11:3c      printf("This was changed by me. /n");2:3c3:3c      printf("This will be changed by me. /n");====31:7c2:7c      printf("This will be changed by you./n");3:7c      printf("This was changed by you./n");注:在没有参数的情况下,diff3产生的输出说明了那行更改.====1和====3指明造成同原始文件不同的是哪一个修改文件.编号方式基于参数序列.也就是第1个文件和第3个文件与原文件不同.1:3c      printf("This was changed by me. /n");3:3c      printf("This will be changed by me. /n");1:3c表示第1个文件的第3行与3:3c表示的第3个文件的第3行不同.为什么不显示与原文件的比较呢。因为第3个文件的第3行与源文件(第2个文件)相同.所以与哪个文件比较无所谓了.2:7c      printf("This will be changed by you./n");3:7c      printf("This was changed by you./n");2:7c表示第2个文件的第7行与3:7c表示的第3个文件的第7行不同.diff3会试图为我们进行合并.合并是在源文件的基础上,依据两个新文件进行修改源文件是第二个文件,第一个文件和第三个文件可以互换,但他们必须有共同的祖先,就是第二个文件.#######################################diff3 -m me.c orig.c you.c |cat -n输出:     1    void foo(void)     2    {     3        printf("This was changed by me. /n");     4         5        printf("This will be unchanged,/n");     6         7        printf("This was changed by you./n");     8    }########################################为了测试更复杂的环境,新建一个文件orig.c.1内容如下:########################################vi orig.c.1 void foo(void){    printf("This will be changed by both of us./n");}########################################用diff3 -m再次比较输出,如下:########################################diff3 -m me.c orig.c.1 you.c void foo(void){<<<<<<< me.c    printf("This was changed by me. /n");    printf("This will be unchanged,/n");    printf("This will be changed by you./n");||||||| orig.c.1    printf("This will be changed by both of us./n");=======    printf("This will be changed by me. /n");    printf("This will be unchanged,/n");    printf("This was changed by you./n");>>>>>>> you.c}########################################注释:以上的格式,同cvs update,需要人工合并文件的格式是一致的.


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