IFS=' /t/n/ 与IFS=$' /t/n'的区别

参考：http://bbs.chinaunix.net/thread-1748468-1-1.html

 

man bash，可以看到这句话：

 

Words of the form $'string' are treated specially.  The word expands to string, with backslash-escaped characters replaced  as  speci-
       fied by the ANSI C standard.  Backslash escape sequences, if present, are decoded as follows:
              /a     alert (bell)
              /b     backspace
              /e     an escape character
              /f     form feed
              /n     new line
              /r     carriage return
              /t     horizontal tab
              /v     vertical tab
              //     backslash
              /'     single quote
              /nnn   the eight-bit character whose value is the octal value nnn (one to three digits)
              /xHH   the eight-bit character whose value is the hexadecimal value HH (one or two hex digits)
              /cx    a control-x character

 

意思就是说： $'String' 这种类型会特殊处理，''内的meta元数据是没被关闭的，会被replaced。

这似乎解决了是"echo输出/t（ 四个空格）"的另一个答案，只在显示时有用？

eg:

[Gary@localhost ~]$ echo '/t'
/t
[Gary@localhost ~]$ echo $'/t'

[Gary@localhost ~]$ echo $'/t'abvc
        abvc

[Gary@localhost ~]$ echo -e "/ta"
        a
[Gary@localhost ~]$ echo /t
t
[Gary@localhost ~]$