国内好的设计网站,西安网站建设瑞信,一个简单的网站怎么做的,上海出国留学中介云栖号资讯#xff1a;【点击查看更多行业资讯】 在这里您可以找到不同行业的第一手的上云资讯#xff0c;还在等什么#xff0c;快来#xff01; 正则表达式是一种字符模式#xff0c;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#xff1a;
Shell… 云栖号资讯【点击查看更多行业资讯】 在这里您可以找到不同行业的第一手的上云资讯还在等什么快来 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 grepgrep --colorauto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. Its 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. Its 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. Its 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. Its 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. Its hard to get back in the
groove.重复前一个字符一个或一个以
$ egrep god linux.txt
Linux is a good
god assdxw bcvnbvbjk
gooodfs awrerdxxhkl
good0个或者一个字符
anshengUbuntu:/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
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