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  • 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

    vi设计http://www.maiqicn.com 办公资源网站大全https://www.wode007.com

    $ egrep "g(la|oo)d" linux.txt
    Linux is a good
    glad
    good
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  • 原文地址:https://www.cnblogs.com/xiaonian8/p/13724641.html
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