17 个案例带你 5 分钟搞定 Linux 正则表达式
正则表达式是一种字符模式，用于在查找过程中匹配制定的字符。
元字符通常在Linux中分为两类：
- Shell元字符，由Linux Shell进行解析；
- 正则表达式元字符，由vi/grep/sed/awk等文本处理工具进行解析；
正则表达式一般以文本行进行处理，在进行下面实例之前，先为grep命令设置—color参数：
$?alias?grep='grep?--color=auto'?这样每次过滤出来的字符串都会带色彩了。
在开始之前还需要做一件事情，就是创建一个测试用的re-file文件，内容如下：
$?cat?re-file??I?had?a?lovely?time?on?our?little?picnic.??Lovers?were?all?around?us.?It?is?springtime.?Oh??love,?how?much?I?adore?you.?Do?you?know??the?extent?of?my?love??Oh,?by?the?way,?I?think??I?lost?my?gloves?somewhere?out?in?that?field?of??clover.?Did?you?see?them??I?can?only?hope?love.??is?forever.?I?live?for?you.?It's?hard?to?get?back?in?the??groove.?正则表达式元字符
特殊的元字符
扩展的正则表达式
实操
匹配以love开头的所有行
$?grep?'^love'?re-file??love,?how?much?I?adore?you.?Do?you?know?匹配love结尾的所有行
$?grep?'love$'?re-file??clover.?Did?you?see?them??I?can?only?hope?love.?匹配以l开头，中间包含两个字符，结尾是e的所有行
$?grep?'l..e'?re-file??I?had?a?lovely?time?on?our?little?picnic.??love,?how?much?I?adore?you.?Do?you?know??the?extent?of?my?love??Oh,?by?the?way,?I?think??I?lost?my?gloves?somewhere?out?in?that?field?of??clover.?Did?you?see?them??I?can?only?hope?love.??is?forever.?I?live?for?you.?It's?hard?to?get?back?in?the?匹配0个或多个空行，后面是love的字符
$?grep?'?*love'?re-file??I?had?a?lovely?time?on?our?little?picnic.??love,?how?much?I?adore?you.?Do?you?know??the?extent?of?my?love??Oh,?by?the?way,?I?think??I?lost?my?gloves?somewhere?out?in?that?field?of??clover.?Did?you?see?them??I?can?only?hope?love.?匹配love或Love
$?grep?'[Ll]ove'?re-file?#?对l不区分大小写??I?had?a?lovely?time?on?our?little?picnic.??Lovers?were?all?around?us.?It?is?springtime.?Oh??love,?how?much?I?adore?you.?Do?you?know??the?extent?of?my?love??Oh,?by?the?way,?I?think??I?lost?my?gloves?somewhere?out?in?that?field?of??clover.?Did?you?see?them??I?can?only?hope?love.?匹配A-Z的字母，其次是ove
$?grep?'[A-Z]ove'?re-file??Lovers?were?all?around?us.?It?is?springtime.?Oh?匹配不在A-Z范围内的任何字符行，所有的小写字符
$?grep?'[^A-Z]'?re-file??I?had?a?lovely?time?on?our?little?picnic.??Lovers?were?all?around?us.?It?is?springtime.?Oh??love,?how?much?I?adore?you.?Do?you?know??the?extent?of?my?love??Oh,?by?the?way,?I?think??I?lost?my?gloves?somewhere?out?in?that?field?of??clover.?Did?you?see?them??I?can?only?hope?love.??is?forever.?I?live?for?you.?It's?hard?to?get?back?in?the??groove.?匹配love.
$?grep?'love.'?re-file??clover.?Did?you?see?them??I?can?only?hope?love.?匹配空格
$?grep?'^$'?re-file?匹配任意字符
$?grep?'.*'?re-file??I?had?a?lovely?time?on?our?little?picnic.??Lovers?were?all?around?us.?It?is?springtime.?Oh??love,?how?much?I?adore?you.?Do?you?know??the?extent?of?my?love??Oh,?by?the?way,?I?think??I?lost?my?gloves?somewhere?out?in?that?field?of??clover.?Did?you?see?them??I?can?only?hope?love.??is?forever.?I?live?for?you.?It's?hard?to?get?back?in?the??groove.?前面o字符重复2到4次
$?grep?'o{2,4}'?re-file??groove.?重复o字符至少2次
$?grep?'o{2,}'?re-file??groove.?重复0字符最多2次
$?grep?'o{,2}'?re-file??I?had?a?lovely?time?on?our?little?picnic.??Lovers?were?all?around?us.?It?is?springtime.?Oh??love,?how?much?I?adore?you.?Do?you?know??the?extent?of?my?love??Oh,?by?the?way,?I?think??I?lost?my?gloves?somewhere?out?in?that?field?of??clover.?Did?you?see?them??I?can?only?hope?love.??is?forever.?I?live?for?you.?It's?hard?to?get?back?in?the??groove.?重复前一个字符一个或一个以
$?egrep?"go+d"?linux.txt??Linux?is?a?good??god?assdxw?bcvnbvbjk??gooodfs?awrerdxxhkl??good?0个或者一个字符
ansheng@Ubuntu:/tmp$?egrep?"go?d"?linux.txt??god?assdxw?bcvnbvbjk??gdsystem?awxxxx?或，查找多个字符串
$?egrep?"gd|good"?linux.txt??Linux?is?a?good??gdsystem?awxxxx??good?分组过滤匹配
$?egrep?"g(la|oo)d"?linux.txt??Linux?is?a?good??glad??good?- 发表于:
- 原文链接：http://news.51cto.com/art/202003/613429.htm
- 如有侵权，请联系 cloudcommunity@tencent.com 删除。
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