sed -r 扩展正则表达式 --举例说明

1cpuer

r 为何物
  -r, --regexp-extended
                 在脚本中使用扩展正则表达式

--举例说明
2，3个 优加
# [ /home/soio/1bs/awks ] {2018-05-05 10:14:00}
: 1525486440:0;➜  echo "\!@#()$%^" | sed 's/(/ar/'
!@#ar)$%^


# [ /home/soio/1bs/awks ] {2018-05-05 10:15:15}
: 1525486515:0;➜  echo "\!@#()$%^" | sed -r 's/\(/ar/'
!@#ar)$%^


# [ /home/soio/1bs/awks ] {2018-05-05 10:15:25}
: 1525486525:0;➜  echo "\!@#()$%^" | sed -r 's/(/ar/'
sed: -e 表达式 #1, 字符 7: 不匹配的 ( 或 \(↵

o枫叶o飘零

   Basic vs Extended Regular Expressions
       In  basic regular expressions the meta-characters ?, +, {, |, (, and ) lose their special meaning; instead use the
       backslashed versions \?, \+, \{, \|, \(, and \).

       Traditional egrep did not support the { meta-character, and some egrep  implementations  support  \{  instead,  so
       portable scripts should avoid { in grep -E patterns and should use [{] to match a literal {.

       GNU grep -E attempts to support traditional usage by assuming that { is not special if it would be the start of an
       invalid interval specification.  For example, the command grep -E ’{1’ searches for the  two-character  string  {1
       instead  of  reporting  a syntax error in the regular expression.  POSIX allows this behavior as an extension, but
       portable scripts should avoid it.

1cpuer

回复 2# o枫叶o飘零

# [ /home/soio/1bs/awks ] {2018-05-05 17:07:31}
: 1525511251:0;➜  echo "123 abc 24_cd" | grep  '[[:alnum:]]'  
123 abc 24_cd


# [ /home/soio/1bs/awks ] {2018-05-05 17:09:51}
: 1525511391:0;➜  echo "123 abc 24_cd" | grep  '[[:alnum:]_]'
123 abc 24_cd


# [ /home/soio/1bs/awks ] {2018-05-05 17:09:54}
: 1525511394:0;➜  echo "123 abc 24_cd" | grep  '\w'           
123 abc 24_cd


# [ /home/soio/1bs/awks ] {2018-05-05 17:10:02}
: 1525511402:0;➜  echo "123 abc 24_cd" | grep  '[^\w_]'      
123 abc 24_cd

5).正则表达式的扩展

额外的GNU正则表达式运算符

运算符

含义

\w:

任何单词组成字符，相当于[[:alnum:]_]

\W:

任何非单词组成字符，相当于[^[:alnum:]_]