用awk写的base64编码脚本，大家帮忙修改一下！

Herowinter

回复 1# bikkuri

开始有这个错误，好象是说and lshift rshift是内建函数，
不能重定义；

1. ./base64.sh Hello
   
2. awk: cmd. line:9:     function and(var,x,l_res,l_i)
   
3. awk: cmd. line:9:              ^ `and' is a built-in function, it cannot be redefined
   
4. awk: cmd. line:21:     function lshift(var,x)
   
5. awk: cmd. line:21:              ^ `lshift' is a built-in function, it cannot be redefined
   
6. awk: cmd. line:30:     function rshift(var,x)
   
7. awk: cmd. line:30:              ^ `rshift' is a built-in function, it cannot be redefined

复制代码

然后我把and  lshift rshift改名为
base64_and, base64_lshift,  base64_rshift好像就有输出了

1. ./base64.sh Hello
   
2. Hello
   
3. 
   
4. Base64 encoded: SGVsbG8=World
   
5. 
   
6. Base64 encoded: SGVsbG8=V29ybGQ=Magic
   
7. 
   
8. Base64 encoded: SGVsbG8=V29ybGQ=TWFnaWM=
   

复制代码

不理解base64算法，不知道结果对不对。
测试环境：CentOS release 6.4   GNU Awk 3.1.7






   

Herowinter

回复 15# bikkuri
好像确实有这个问题
CentOS6.4

1. echo -e "Hello\0World"|awk '1'
   
2. 
   
3. HelloWorld

复制代码

Solaris 5.10

1. echo -e "Hello\0World"|/usr/xpg4/bin/awk '1'
   
2. 
   
3. Hello

复制代码

gawk和nawk的区别？

Herowinter

回复 14# bikkuri

找了一上午，没找到怎么忽略输入中的\0的。
楼主看一一下下面这段，gawk外的其他awk
都是以\0为结束的。


Advanced Notes: RS = "\0" Is Not Portable

There are times when you might want to treat an entire data file as a single record. The only way to make this happen is to give RS a value that you know doesn't occur in the input file. This is hard to do in a general way, such that a program always works for arbitrary input files.

You might think that for text files, the NUL character, which consists of a character with all bits equal to zero, is a good value to use for RS in this case:

       

BEGIN { RS = "\0" }  # whole file becomes one record?

gawk in fact accepts this, and uses the NUL character for the record separator. However, this usage is not portable to other awk implementations.

All other awk implementations(15) store strings internally as C-style strings. C strings use the NUL character as the string terminator. In effect, this means that `RS = "\0"' is the same as `RS = ""'. (d.c.)

The best way to treat a whole file as a single record is to simply read the file in, one record at a time, concatenating each record onto the end of the previous ones.

   

Herowinter

回复 22# bikkuri
awk本来就不是很适合处理2进制文件，
你可以参考一下这篇文章，
http://www.ibm.com/developerworks/cn/linux/shell/awk/binary/

试试类似这种行不行

1. echo -e "Hello\0World"|od|./base64encode.sh

复制代码

我是完全看不懂出来的结果对不对。

Herowinter

回复 24# bikkuri
目测的，不大确定行不行。

1. cat a.gz|hexdump -C
   
2. 
   
3. 00000000  1f 8b 08 08 02 0f bd 52  00 03 61 00 f3 48 cd c9  |.......R..a..H..|
   
4. 00000010  c9 0f cf 2f ca 49 e1 02  00 07 b8 79 1b 0b 00 00  |.../.I.....y....|
   
5. 00000020  00                                                |.|
   
6. 00000021
   
7. 
   
8. 
   
9. cat a.gz|hexdump -C|awk '{for(i=2;i<NF;i++)s=s$i}END{print s}'
   
10. 
    
11. 1f8b0808020fbd5200036100f348cdc9c90fcf2fca49e1020007b8791b0b000000

复制代码

Herowinter

回复 26# bikkuri

1. cat a.gz|hexdump -C|awk '{for(i=2;i<NF;i++)s=s?s" "$i:$i}END{print s}'
   
2. 
   
3. 1f 8b 08 08 02 0f bd 52 00 03 61 00 f3 48 cd c9 c9 0f cf 2f ca 49 e1 02 00 07 b8 79 1b 0b 00 00 00

复制代码

Herowinter

回复 27# bikkuri
判断一下s是否非空再拼空格就没有第一个空格了。

   

Herowinter

回复 31# bikkuri
我是参照那个样本数据写的代码，取得是2到NF-1这些字段，
可能处理实际数据，会有些偏差，可以加个正则判断每一个
$i是不是[0-9a-f]{2}就不会取到乱码了。

1. echo "c4 0f 18 f8 |.(^=|. 61 1a e1"|awk --re-interval '{for(i=2;i<NF;i++)if($i~/[0-9a-f]{2}/)s=s?s" "$i:$i}END{print s}'
   
2. 
   
3. 0f 18 f8 61 1a

复制代码

Herowinter

回复 32# bikkuri
substr好像不影响$0,$1的吧，不理解。


   

Herowinter

回复 39# damcool
精通规范的业内人士来了，咱们这种背景不熟
的遇到救星了。