Linux basic--grep and regular expressions

The basic usage of grep can be referred to in this [link] document, written in detail, here is the main description of the use of regular expressions.

1. GREP supports the basic regular Expressions (BRE) and extended regular Expressions (ERE) by default.

2. Fgrep does not support regular expressions and does not need to load the regular expression engine, so it is faster.

3. The Egrep only supports extended regular expressions (ERE).
   

4. ' Egrep ' means ' grep-e '. ' Fgrep ' means ' grep-f '.

The extended regular expression (ERE) differs from the basic regular expression (BRE), and the matching rules in the BRE also apply in the Ere, but ere the use of some meta-characters and symbols without the ' \ ' escape, and Ere adds a ' | ' The symbol represents the logical OR.

So it is not intended to introduce the BRE and Ere separately, the following does not indicate the use of ere separately, the description is consistent with the BRE usage.

650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M00/7D/01/wKiom1beVinCrWsrAABZfIxu7Wo939.png "title=" Grep_ 001.png "width=" height= "131" border= "0" hspace= "0" vspace= "0" style= "width:700px;height:131px;" alt= " Wkiom1bevincrwsraabzfixu7wo939.png "/>

650) this.width=650; "src=" Http://s2.51cto.com/wyfs02/M02/7D/01/wKiom1beVsaTt5X8AADJSJpgzR0610.png "title=" Grep_ 002.png "width=" height= "333" border= "0" hspace= "0" vspace= "0" style= "width:700px;height:333px;" alt= " Wkiom1bevsatt5x8aadjsjpgzr0610.png "/>

650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M00/7D/00/wKioL1beWAbgZ1mvAABmBCnvV7o027.png "title=" Grep_ 003.png "width=" height= "141" border= "0" hspace= "0" vspace= "0" style= "width:700px;height:141px;" alt= " Wkiol1bewabgz1mvaabmbcnvv7o027.png "/>

650) this.width=650; "src=" Http://s5.51cto.com/wyfs02/M02/7D/01/wKiom1beV-ySozPAAABaMXVILW4259.png "title=" Grep_ 004.png "width=" height= "138" border= "0" hspace= "0" vspace= "0" style= "width:700px;height:138px;" alt= " Wkiom1bev-ysozpaaabamxvilw4259.png "/>

650) this.width=650; "src=" Http://s2.51cto.com/wyfs02/M00/7D/00/wKioL1beWSzDlf3GAABu-0jW_gE833.png "title=" Grep_ 005.png "Width=" height= "182" border= "0" hspace= "0" vspace= "0" style= "width:700px;height:182px;" alt= " Wkiol1bewszdlf3gaabu-0jw_ge833.png "/>

650) this.width=650; "src=" Http://s2.51cto.com/wyfs02/M02/7D/01/wKiom1beWPiSAEA9AAClbbYi6CE907.png "title=" Grep_ 006.png "width=" height= "279" border= "0" hspace= "0" vspace= "0" style= "WIDTH:700PX;HEIGHT:279PX;" alt= " Wkiom1bewpisaea9aaclbbyi6ce907.png "/>

650) this.width=650; "src=" Http://s1.51cto.com/wyfs02/M00/7D/00/wKioL1beWiCSJ3byAABwkPb_Bkc471.png "title=" Grep_ 007.png "width=" height= "188" border= "0" hspace= "0" vspace= "0" style= "width:700px;height:188px;" alt= " Wkiol1bewicsj3byaabwkpb_bkc471.png "/>

650) this.width=650; "src=" Http://s5.51cto.com/wyfs02/M02/7D/01/wKiom1beWfSCu2LuAAF4CeMxuPg846.png "title=" Grep_ 008.png "width=" height= "631" border= "0" hspace= "0" vspace= "0" style= "width:700px;height:631px;" alt= " Wkiom1bewfscu2luaaf4cemxupg846.png "/>

650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M01/7D/00/wKioL1beW5Lgrd8qAABsIQ9wG3k139.png "title=" Grep_ 009.png "width=" height= "167" border= "0" hspace= "0" vspace= "0" style= "WIDTH:700PX;HEIGHT:167PX;" alt= " Wkiol1bew5lgrd8qaabsiq9wg3k139.png "/>

650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M00/7D/01/wKiom1beW2PyKy-AAABSI3gjhrQ067.png "title=" Grep_ 010.png "width=" height= "119" border= "0" hspace= "0" vspace= "0" style= "WIDTH:700PX;HEIGHT:119PX;" alt= " Wkiom1bew2pyky-aaabsi3gjhrq067.png "/>

650) this.width=650; "src=" Http://s4.51cto.com/wyfs02/M00/7D/00/wKioL1beXEfSgAq9AAB3pPKZDLs828.png "title=" Grep_ 011.png "width=" height= "169" border= "0" hspace= "0" vspace= "0" style= "WIDTH:700PX;HEIGHT:169PX;" alt= " Wkiol1bexefsgaq9aab3ppkzdls828.png "/>

650) this.width=650; "src=" Http://s1.51cto.com/wyfs02/M01/7D/01/wKiom1beXBfBewO2AABT4V1gTF8700.png "title=" Grep_ 012.png "width=" height= "122" border= "0" hspace= "0" vspace= "0" style= "width:700px;height:122px;" alt= " Wkiom1bexbfbewo2aabt4v1gtf8700.png "/>

650) this.width=650; "src=" Http://s4.51cto.com/wyfs02/M01/7D/00/wKioL1beXUzS9g5pAABTeYCTFiQ769.png "title=" Grep_ 013.png "width=" height= "122" border= "0" hspace= "0" vspace= "0" style= "width:700px;height:122px;" alt= " Wkiol1bexuzs9g5paabteyctfiq769.png "/>

The above results are generated using this [script] and can be downloaded for validation. The terminal connection tool needs to support the display color and the system character set to Chinese.

[Email protected] ~]# wget https://raw.githubusercontent.com/twoyang0917/LearnInMagedu/master/shell/grep_show.sh [ [Email protected] ~]# bash grep_show.sh

This article is from the "knfprex3a29" blog, make sure to keep this source http://knfprex3a29.blog.51cto.com/9761463/1748712

Linux basic--grep and regular expressions