摘要：本文詳細介紹了diff命令的基本用法
作者：zieckey （zieckey＠yahoo.com.cn）
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有這樣兩個文件：
程序清單1 ：hello.c
#include <stdio.h>
int main(void)
{
char msg[] = "Hello world!";
puts(msg);
printf("Welcome to use diff commond.\n");
return 0;
}
程序清單2：hello_diff.c
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
char msg[] = "Hello world,fome hello_diff.c";
puts(msg);
printf("hello_diff.c says,'Here you are,using diff.'\n");
return 0;
}
我們使用diff命令來查看這兩個文件的不同之處，有一下幾種方便的方法：
1、普通格式輸出：
[root@localhost diff]# diff hello.c hello_diff.c
1a2
> #include <stdlib.h>
5c6
< char msg[] = "Hello world!";
---
> char msg[] = "Hello world,fome hello_diff.c";
8c9
< printf("Welcome to use diff commond.\n");
---
> printf("hello_diff.c says,'Here you are,using diff.'\n");
[root@localhost diff]#
上面的“1a2”表示後面的一個文件"hello_diff.c"比前面的一個文件"hello.c"多了一行
"5c6"表示第一個文件的第5行與第二個文件的第6行有區別
2、並排格式輸出
[root@localhost diff]# diff hello.c hello_diff.c -y -W 130
#include <stdio.h> #include <stdio.h>
> #include <stdlib.h>
int main(void) int main(void)
{ {
char msg[] = "Hello world!"; | char msg[] = "Hello world,fome hello_diff.c";
puts(msg); puts(msg);
printf("Welcome to use diff commond.\n"); | printf("hello_diff.c says,'Here you are,using diff.'\
return 0; return 0;
} }
[root@localhost diff]#
這種並排格式的對比一目瞭然，可以快速找到不同的地方。
-W選擇可以指定輸出列的寬度，這裏指定輸出列寬爲130
3、上下文輸出格式
[root@localhost diff]# diff hello.c hello_diff.c -c
*** hello.c 2007-09-25 17:54:51.000000000 +0800
--- hello_diff.c 2007-09-25 17:56:00.000000000 +0800
***************
*** 1,11 ****
#include <stdio.h>
int main(void)
{
! char msg[] = "Hello world!";
puts(msg);
! printf("Welcome to use diff commond.\n");
return 0;
}
--- 1,12 ----
#include <stdio.h>
+ #include <stdlib.h>
int main(void)
{
! char msg[] = "Hello world,fome hello_diff.c";
puts(msg);
! printf("hello_diff.c says,'Here you are,using diff.'\n");
return 0;
}
[root@localhost diff]#
這種方式在開頭兩行作了比較文件的說明，這裏有三中特殊字符：
＋ 比較的文件的後者比前着多一行
－ 比較的文件的後者比前着少一行
！ 比較的文件兩者有差別的行
4、統一輸出格式
[root@localhost diff]# diff hello.c hello_diff.c -u
--- hello.c 2007-09-25 17:54:51.000000000 +0800
+++ hello_diff.c 2007-09-25 17:56:00.000000000 +0800
@@ -1,11 +1,12 @@
#include <stdio.h>
+#include <stdlib.h>
int main(void)
{
- char msg[] = "Hello world!";
+ char msg[] = "Hello world,fome hello_diff.c";
puts(msg);
- printf("Welcome to use diff commond.\n");
+ printf("hello_diff.c says,'Here you are,using diff.'\n");
return 0;
}
[root@localhost diff]#
正如看到的那樣，統一格式的輸出更加緊湊，所以更易於理解，更易於修改。
5、其他
假如你想查看兩個文件是否不同又不想顯示差異之處的話，可以加上－q選項：
[root@localhost diff]# diff hello.c hello_diff.c -q
Files hello.c and hello_diff.c differ
[root@localhost diff]# 另外你還可以提供一些匹配規則來忽略某中差別，可以用 -I regexp
[root@localhost diff]# diff hello.c hello_diff.c -c -I include
*** hello.c 2007-09-25 17:54:51.000000000 +0800
--- hello_diff.c 2007-09-25 17:56:00.000000000 +0800
***************
*** 2,11 ****
int main(void)
{
! char msg[] = "Hello world!";
puts(msg);
! printf("Welcome to use diff commond.\n");
return 0;
}
--- 3,12 ----
int main(void)
{
! char msg[] = "Hello world,fome hello_diff.c";
puts(msg);
! printf("hello_diff.c says,'Here you are,using diff.'\n");
return 0;
}
[root@localhost diff]#
這裏通過“ -I include”選項來忽略帶有“ include”字樣的行