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標(biāo)題: awk包含匹配正則表達(dá)式問題 [打印本頁]

作者: mgqw 時間: 2012-04-19 16:13
標(biāo)題: awk包含匹配正則表達(dá)式問題
本帖最后由 mgqw 于 2012-04-19 16:15 編輯

為什么我直接匹配兩個'+'號 /^\+\+/ 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

$ cat svn.log
+++ xxxconfig.js
+ 'xxxSettingInfo'
+ 'xxxChangeSet'
+++ yyyconfig.js
+ 'yyySettingInfo'
+ 'yyyChangeSet'
$
$
$ awk '{ if($1~/^\+\+/){print $0} }' ./svn.log
+++ xxxconfig.js
+++ yyyconfig.js
$
$
$
$ awk '{ if($1~/^\+{2,}/){print $0} }' ./svn.log
$
$
$

復(fù)制代碼

作者: waker 時間: 2012-04-19 16:17
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.

作者: mgqw 時間: 2012-04-19 16:28
回復(fù) 2# waker

版主威武, 這么快就回答了!~

作者: justlooks 時間: 2012-04-19 16:30
# echo "+++ abc"|awk --posix '/^\+{2,}/'
+++ abc

作者: waker 時間: 2012-04-19 16:32
說明你發(fā)了個經(jīng)帖

作者: mgqw 時間: 2012-04-19 16:36
我有罪......

作者: mpstat 時間: 2012-04-19 16:40
   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.

作者: yjcdoc 時間: 2012-04-19 17:44
用--re-interval 參數(shù)可以

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