3分钟搞定Linux系统正则表达式

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：

class="">$aliasgrep='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：

class="">$catre-fileIhadalovelytimeonourlittlepicnic.
Loverswereallaroundus.Itisspringtime.Oh
love,howmuchIadoreyou.Doyouknow
theextentofmylove?Oh,bytheway,Ithink
Ilostmyglovessomewhereoutinthatfieldof
clover.Didyouseethem?Icanonlyhopelove.
isforever.Iliveforyou.It'shardtogetbackinthe
groove.

class="">$catlinux.txtLinuxisagood
godassdxwbcvnbvbjk
greattttttwexcvxc
operaaaatingdhfghfvx
gooodfsawrerdxxhkl
gdsystemawxxxx
glad
good

正则表达式元字符

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：

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

class="">$grep'^love're-filelove,howmuchIadoreyou.Doyouknow

匹配love结尾的所有行

class="">$grep'love$'re-fileclover.Didyouseethem?Icanonlyhopelove.

匹配以l开头，中间包含两个字符，结尾是e的所有行

class="">$grep'l..e're-fileIhadalovelytimeonourlittlepicnic.
love,howmuchIadoreyou.Doyouknow
theextentofmylove?Oh,bytheway,Ithink
Ilostmyglovessomewhereoutinthatfieldof
clover.Didyouseethem?Icanonlyhopelove.
isforever.Iliveforyou.It'shardtogetbackinthe

匹配0个或多个空行，后面是love的字符

class="">$grep'*love're-fileIhadalovelytimeonourlittlepicnic.
love,howmuchIadoreyou.Doyouknow
theextentofmylove?Oh,bytheway,Ithink
Ilostmyglovessomewhereoutinthatfieldof
clover.Didyouseethem?Icanonlyhopelove.

匹配love或Love

class="">$grep'[Ll]ove're-file#对l不区分大小写Ihadalovelytimeonourlittlepicnic.
Loverswereallaroundus.Itisspringtime.Oh
love,howmuchIadoreyou.Doyouknow
theextentofmylove?Oh,bytheway,Ithink
Ilostmyglovessomewhereoutinthatfieldof
clover.Didyouseethem?Icanonlyhopelove.

匹配A-Z的字母，其次是ove

class="">$grep'[A-Z]ove're-fileLoverswereallaroundus.Itisspringtime.Oh

匹配不在A-Z范围内的任何字符行，所有的小写字符

class="">$grep'[^A-Z]'re-fileIhadalovelytimeonourlittlepicnic.
Loverswereallaroundus.Itisspringtime.Oh
love,howmuchIadoreyou.Doyouknow
theextentofmylove?Oh,bytheway,Ithink
Ilostmyglovessomewhereoutinthatfieldof
clover.Didyouseethem?Icanonlyhopelove.
isforever.Iliveforyou.It'shardtogetbackinthe
groove.

匹配love

class="">$grep'love.'re-fileclover.Didyouseethem?Icanonlyhopelove.

匹配空格

class="">$grep'^$'re-file

匹配任意字符

class="">$grep'.*'re-fileIhadalovelytimeonourlittlepicnic.
Loverswereallaroundus.Itisspringtime.Oh
love,howmuchIadoreyou.Doyouknow
theextentofmylove?Oh,bytheway,Ithink
Ilostmyglovessomewhereoutinthatfieldof
clover.Didyouseethem?Icanonlyhopelove.
isforever.Iliveforyou.It'shardtogetbackinthe
groove.

前面o字符重复2到4次

class="">$grep'o{2,4}'re-filegroove.

重复o字符至少2次

class="">$grep'o{2,}'re-filegroove.

重复0字符最多2次

class="">$grep'o{,2}'re-fileIhadalovelytimeonourlittlepicnic.
Loverswereallaroundus.Itisspringtime.Oh
love,howmuchIadoreyou.Doyouknow
theextentofmylove?Oh,bytheway,Ithink
Ilostmyglovessomewhereoutinthatfieldof
clover.Didyouseethem?Icanonlyhopelove.
isforever.Iliveforyou.It'shardtogetbackinthe
groove.

开发云主机域名

重复前一个字符一个或一个以上

class="">$egrep"go+d"linux.txtLinuxisagood
godassdxwbcvnbvbjk
gooodfsawrerdxxhkl
good#####0个或者一个字符ansheng@Ubuntu:/tmp$egrep"go?d"linux.txt
godassdxwbcvnbvbjk
gdsystemawxxxx

或，查找多个字符串

class="">$egrep"gd|good"linux.txtLinuxisagood
gdsystemawxxxx
good

分组过滤匹配

class="">$egrep"g(la|oo)d"linux.txtLinuxisagood
glad
good

实操