awk包含匹配正則表達(dá)式問(wèn)題

mgqw

為什么我直接匹配兩個(gè)'+'號(hào) /^\+\+/ 能匹配上,
而用正則表達(dá)式 /^\+{2,}/ 匹配兩次以上就匹配不上了,
為什么呢? 求解釋

1. $ cat svn.log
   
2. +++ xxxconfig.js
   
3. +               'xxxSettingInfo'         
   
4. +               'xxxChangeSet'           
   
5. +++ yyyconfig.js
   
6. +               'yyySettingInfo'
   
7. +               'yyyChangeSet'
   
8. 
   
9. $
   
10. $
    
11. $ awk '{ if($1~/^\+\+/){print $0} }' ./svn.log  
    
12. +++ xxxconfig.js
    
13. +++ yyyconfig.js
    
14. $
    
15. $
    
16. $
    
17. $ awk '{ if($1~/^\+{2,}/){print $0} }' ./svn.log
    
18. $
    
19. $
    
20. $
    

復(fù)制代碼

waker

Interval expressions were not traditionally available in awk. They were added as part of the POSIX standard to make awk and egrep consistent with each other.

Initially, because old programs may use ‘{’ and ‘}’ in regexp constants, gawk did not match interval expressions in regexps.

mgqw

回復(fù) 2# waker


    版主威武, 這么快就回答了!~

justlooks

# echo "+++ abc"|awk --posix '/^\+{2,}/'
+++ abc

waker

說(shuō)明你發(fā)了個(gè)經(jīng)帖

mgqw

我有罪......

mpstat

       r{n,m}     One or two numbers inside braces denote an interval expression.  If there is one number in the braces, the preceding regular  expression
                  r is repeated n times.  If there are two numbers separated by a comma, r is repeated n to m times.  If there is one number followed by a
                  comma, then r is repeated at least n times.
                  Interval expressions are only available if either --posix or --re-interval is specified on the command line.

yjcdoc

用--re-interval 參數(shù)可以