Linux 正则表达式_010
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? ? Linux 正则表达式 ? ? 标注：本教程只针对linux运维的三剑客命令awk，sed，grep正则表达式 ? ? 什么是正则表达式？ 简单的说，正则表达式就是为处理大量的字符串而定义的一套规则和方法通过定义的这些特殊符号的辅助， 系统管理员就可以快速过滤，替换或输出需要的字符串，linux正则表达式一般以行为单位处理 ? ? 为什么要学会正则表达式? 在企业工作中，我们每天做的linux运维工作中， 时刻都会面对大量带有字符串的文本配置、程序、命令输出及日志文件等， 而我们经常会有迫切的需要，从大量的字符串内容中查找符合工作需要的特定字符串。这就要靠正则表达式。因此，可以说正则 表达式就是为过滤这样字符串的需求而生Llinux最常应用的正则表达式的命令 grep(egrep)/sed/awk,换名话说linux三剑客要想能 工作的更高效，那一定离不开正则表达式配合。 ? ? 正则表达式注意事项 1、linux正则表达式一般以行为单位处理的 2、设置别名alias grep=‘grep --color=auto‘,让匹配的内容显示颜色 3、注意字符集，使用LC_ALL=C，在/etc/profile配置文件最后添加一行export LC_ALL=C 4、注意使用单引号和双引号，建议使用双引号 ? ? ?
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? ? ? ? 举例(以grep为例子讲解) ? [[email?protected] ~]# cat file.txt I am oldboy teacher! I teach linux. ? I like badminton ball,billiard ball and chinese chess! my blog is http://oldboy.blog.51cto.com our site is http://www.etiantian.org my qq num is 1300052. ? not 130000052. my god,i am not oldboy,but OLDBOY! ? ? 范例1： [[email?protected] ~]# grep "^my" file.txt my blog is http://oldboy.blog.51cto.com my qq num is 1300052. my god,but OLDBOY! [[email?protected] ~]# grep "com$" file.txt my blog is http://oldboy.blog.51cto.com [[email?protected] ~]# grep -n "^$" file.txt 3: 8: [[email?protected] ~]# grep "13...52" file.txt my qq num is 1300052. [[email?protected] ~]# grep "//" file.txt my blog is http://oldboy.blog.51cto.com our site is http://www.etiantian.org [[email?protected] ~]# grep "//" file.txt my blog is http://oldboy.blog.51cto.com our site is http://www.etiantian.org [[email?protected] ~]# grep ‘//‘ file.txt my blog is http://oldboy.blog.51cto.com our site is http://www.etiantian.org [[email?protected] ~]# grep "130*52" file.txt my qq num is 1300052. not 130000052. ? ? 范例2： [[email?protected] ~]# grep ".*" file.txt I am oldboy teacher! I teach linux. ? I like badminton ball,but OLDBOY! [[email?protected] ~]# grep "^my.*" file.txt my blog is http://oldboy.blog.51cto.com my qq num is 1300052. my god,but OLDBOY! [[email?protected] ~]# grep "org.*$" file.txt our site is http://www.etiantian.org [[email?protected] ~]# grep "[0-9]" file.txt my blog is http://oldboy.blog.51cto.com my qq num is 1300052. not 130000052. [[email?protected] ~]# grep "[^a-z]" file.txt I am oldboy teacher! I teach linux. I like badminton ball,billiard ball and chinese chess! my blog is http://oldboy.blog.51cto.com our site is http://www.etiantian.org my qq num is 1300052. not 130000052. my god,but OLDBOY! ? ? 范例3： [[email?protected] ~]# grep -E "0{4,5}" file.txt not 130000052. [[email?protected] ~]# grep -E "0{4,}" file.txt not 130000052. [[email?protected] ~]# grep -E "0{3}" file.txt my qq num is 1300052. not 130000052. [[email?protected] ~]# grep -E "0{,4}" file.txt I am oldboy teacher! I teach linux. ? I like badminton ball,but OLDBOY! ? ? 范例4： [[email?protected] ~]# echo 2oldboy >> file.txt [[email?protected] ~]# echo 3oldboy4 >> file.txt [[email?protected] ~]# grep "oldboy" file.txt I am oldboy teacher! my blog is http://oldboy.blog.51cto.com my god,but OLDBOY! 2oldboy 3oldboy4 [[email?protected] ~]# grep "boldboy" file.txt I am oldboy teacher! my blog is http://oldboy.blog.51cto.com my god,but OLDBOY! [[email?protected] ~]# grep "boldboyb" file.txt I am oldboy teacher! my blog is http://oldboy.blog.51cto.com my god,but OLDBOY! ? ? 范例5： [[email?protected] ~]# grep -E "[0-9]|qq|linux" file.txt I teach linux. my blog is http://oldboy.blog.51cto.com my qq num is 1300052. not 130000052. 2oldboy 3oldboy4 [[email?protected] ~]# egrep "[0-9]|qq|linux" file.txt I teach linux. my blog is http://oldboy.blog.51cto.com my qq num is 1300052. not 130000052. 2oldboy 3oldboy4 ? ? ? ? Linux正则表达式结合三剑客企业级实践 ? 1、取系统IP地址 替换功能 sed ‘s#支持正则位置##g’?? file sed ?-n ‘s#支持正则位置##gp’? file ? [[email?protected] ~]# ifconfig eth3 eth3????? Link encap:Ethernet? HWaddr 00:0C:29:A7:4E:51? ????????? inet addr:10.8.9.65? Bcast:10.8.9.255? Mask:255.255.255.0 ????????? inet6 addr: fe80::20c:29ff:fea7:4e51/64 Scope:Link ????????? UP BROADCAST RUNNING MULTICAST? MTU:1500? Metric:1 ????????? RX packets:134218 errors:0 dropped:0 overruns:0 frame:0 ????????? TX packets:31049 errors:0 dropped:0 overruns:0 carrier:0 ????????? collisions:0 txqueuelen:1000 ???? ?????RX bytes:13502212 (12.8 MiB)? TX bytes:2379801 (2.2 MiB) [[email?protected] ~]# ifconfig eth3 | sed -n ‘2p‘|sed ‘s#^.*dr:##g‘|sed ‘s#? B.*$##g‘ 10.8.9.65 [[email?protected] ~]# ifconfig eth3 | sed -n ‘2s#^.*dr:##gp‘ | sed ‘s#? B.*$##g‘ 10.8.9.65 ? ? 2、sed后向引用 sed -n ?‘s#()()#12#gp‘? file 当在前面匹配部分用小括号的时候，第一个括号内容，可以在后面的部分用1输出。 第二个括号内容，可以在后面的部分用2输出 [[email?protected] ~]# ifconfig eth3 eth3????? Link encap:Ethernet? HWaddr 00:0C:29:A7:4E:51? ????????? inet addr:10.8.9.65? Bcast:10.8.9.255? Mask:255.255.255.0 ????????? inet6 addr: fe80::20c:29ff:fea7:4e51/64 Scope:Link ????????? UP BROADCAST RUNNING MULTICAST? MTU:1500? Metric:1 ????????? RX packets:134828 errors:0 dropped:0 overruns:0 frame:0 ????????? TX packets:31546 errors:0 dropped:0 overruns:0 carrier:0 ????????? collisions:0 txqueuelen:1000 ????????? RX bytes:13565103 (12.9 MiB)? TX bytes:2431777 (2.3 MiB) [[email?protected] ~]# ifconfig eth3 | sed -nr ‘s#^.*dr:(.*)? Bc.*$#1#gp‘ 10.8.9.65 [[email?protected] ~]# stat /etc/hosts | sed -nr ‘s#^.*ess: ((.*)/-.*$#1#gp‘ 0644 [[email?protected] ~]# sed -nr ‘s#([^:]+)(:.*:)(/.*$)#321#gp‘ /etc/passwd | head -4 /bin/bash:x:0:0:root:/root:root /sbin/nologin:x:1:1:bin:/bin:bin /sbin/nologin:x:2:2:daemon:/sbin:daemon /sbin/nologin:x:3:4:adm:/var/adm:adm （编辑：李大同） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
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