用$()和``得出的结果不一样？？求解

quil

1. 
   
2. 测试环境：aix5 ksh;sco5.06 ksh
   
3. 158$ echo \\n123456\\n
   
4. 
   
5. 123456
   
6. 
   
7. 159$ abc=`echo \\n123456\\n`
   
8. 160$ echo $abc
   
9. n123456n
   
10. 161$ echo "$abc"
    
11. n123456n
    
12. 162$ ABC=$(echo \\n123456\\n)
    
13. 163$ echo "$ABC"
    
14. 
    
15. 123456
    
16. 164$ echo $ABC
    
17. 123456
    
18. 165$
    

复制代码

这是从cbbn上看到的一个问题，经过测试发现是$()和``有差别。十三问里没有讲到。哪位大大知道啊

[ 本帖最后由 quil 于 2005-11-9 09:26 编辑 ]

zhhui2000

$ ABC=$(echo \n123456\n);echo $ABC
123456
$ abc=`echo "\n123456\n"`;echo $abc
123456

为什么abc/ABC不等于空？以及楼主的疑问，盼高手。

waker

用$()代替`的好处就是可以正确处理转义符

moonforce

All new scripts should use the $(...) form, which was introduced to avoid some rather complex rules
covering the use of the characters $, `, and  inside the back-quoted command. If a backtick is used within
the `...` construct, it must be escaped with a  character. These relatively obscure characters often con-
fuse programmers, and sometimes even experienced shell programmers are forced to experiment to get the
quoting correct in backticked commands.


《John.Wiley.Sons. Beginning.Linux.Programming,Third.Edition》 chapter 1 , command execution

網中人

是的, $() 跟 `` 是有很多差別的, 只是我一時偷懶, 沒去找了.
主要是對 metacharacter 的處理不一樣.