RH134-01 配合grep使用正则表达式
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第二章、配合grep使用正则表达式 2.1 正则表达式基础 介绍shell中的常用正则表达式 ^ 以什么开头 ^# $ 以什么结尾 y$ . 匹配任意一个字符 .*匹配0个或若干个字符 h*匹配0个h或若干个h h+匹配1个或更多个h h?匹配0个或1个h h{2} 匹配 hh (两个hh) [abc]匹配a或b或c [a-z]匹配所有的小写字符 [A-Z]匹配大写字母 [a-Z]匹配所有字符 [0-9]匹配所有数字 练习：匹配 IP地址的格式，但无需判断IP是否合理。格式要求满足 以 "."分割是四组数字,每组数字可以1~3位数 0.0.0.0- 255.255.255.255 [0-9]{1,3}.[0-9]{1,3} 2.2、使用grep匹配数据 使用grep和正则表达式过滤文件内容和需要的日志内容 练习：建立一个文本/tmp/cats.txt，文本内容如下 cat caaat catdog cat2dog catanddog dogcat ccat catdogcccc c123t c45678t Cat cAt catdogDogCAT #this is a cat ;this is a dog $ grep "cat"/tmp/cats.txt $ grep -i "cat"/tmp/cats.txt 忽略大小写 $ grep ^cat /tmp/cats.txt $ grep dog$ /tmp/cats.txt $ grep ^catdog$ /tmp/cats.txt $ grep ^cat.*dog$ /tmp/cats.txt $ grep ^cat.dog$ /tmp/cats.txt $ grep ^cat...dog$ /tmp/cats.txt $ grep -E^cat.{3}dog$ /tmp/cats.txt 中间3个任意字符 $ grep ^c[0-9]*t$/tmp/cats.txt [0-9]* 匹配0个或若干个数字 $ grep -E^"[#;]" /tmp/cats.txt 以# ;开头的 $ grep -e ^"#"-e ^";" /tmp/cats.txt 作用同上，-e 可以通过指定多个表达式 练习1：过去日志，把 August 8 sometime between 1:00pm and 3:00pm 时间段的日志找到 http://classroom.example.com/pub/materials/awesome_logs/door.log $ grep"Aug 8 1[34]" door.log ========================================================================= 2.2 上课笔记 2．2 [student@localhost tmp]$ cat cats.txt t catdog cat2dog catanddog dogcat ccat catdogcccc c123t c45678t Cat cAt catdogDogCAT #this is a cat ;this is a dog [student@localhost tmp]$ [student@localhost tmp]$ [student@localhost tmp]$ grep"cat" /tmp/cats.txt [student@localhost tmp]$ grep"cat" /tmp/cats.txt catdog cat2dog catanddog dogcat ccat catdogcccc catdogDogCAT #this is a cat [student@localhost tmp]$ grep -i"cat" /tmp/cats.txt catdog cat2dog catanddog dogcat ccat catdogcccc Cat cAt catdogDogCAT #this is a cat [student@localhost tmp]$ [student@localhost tmp]$ grep ^cat/tmp/cats.txt catdog cat2dog catanddog catdogcccc catdogDogCAT [student@localhost tmp]$ 可以对要找的内容加双 引号，也可以不加 [student@localhost tmp]$ grep ^cat /tmp/cats.txt catdog cat2dog catanddog catdogcccc catdogDogCAT [student@localhost tmp]$ ^C [student@localhost tmp]$ grep"^cat" /tmp/cats.txt catdog cat2dog catanddog catdogcccc catdogDogCAT [student@localhost tmp]$ [student@localhost tmp]$ grep dog$/tmp/cats.txt catdog cat2dog catanddog ;this is a dog [student@localhost tmp]$ grep ^catdog$/tmp/cats.txt catdog [student@localhost tmp]$ [student@localhost tmp]$ grep ^cat.*dog$/tmp/cats.txt catdog cat2dog catanddog [student@localhost tmp]$ .*0个或 若干个其他字符 [student@localhost tmp]$ grep ^cat.dog$/tmp/cats.txt cat2dog [student@localhost tmp]$ .表示一个字符 [student@localhost tmp]$ grep -E^cat.{3}dog$ /tmp/cats.txt catanddog [student@localhost tmp]$ grep ^cat...dog$/tmp/cats.txt catanddog [student@localhost tmp]$ 以上两种相同，前者显得更专业 [student@localhost tmp]$ grep ^c[0-9]*t$ /tmp/cats.txt c123t c45678t ct也可以匹配 $ grep -E^"[#;]" /tmp/cats.txt 以# ;开头的 [student@localhost tmp]$ grep -E^"[#;]" /tmp/cats.txt #this is a cat ;this is a dog [student@localhost tmp]$ ifconfig | grep[0-9]{1,3} 对输出结果进行查找 练习： 先下载 下来 [student@localhost tmp]$ wget -O/tmp/door.log http://classroom.example.co m/pub/materials/awesome_logs/door.log --2017-06-25 12:22:01--http://classroom.example.com/pub/materials/awesome_logs/door.log Resolving classroom.example.com(classroom.example.com)... 172.25.254.254 Connecting to classroom.example.com(classroom.example.com)|172.25.254.254|:80... connected. HTTP request sent,awaiting response... 200OK Length: 58722 (57K) [text/plain] Saving to: ‘/tmp/door.log’ 100%[======================================>]58,722 --.-K/s in 0.001s 2017-06-25 12:22:02 (43.6 MB/s) -‘/tmp/door.log’ saved [58722/58722] [student@localhost tmp]$ grep -E "Aug 8 1[34]" /tmp/door.log Aug8之间是两个空格。 考题： Grep “UUID” /etc/fstab >/tmp/find.txt （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! |