linux grep regular expression

Linux basic command grep egrep fgrep usage and regular expression 1. grep, egrep, and fgrep commands this article mainly introduces the basic parameters and usage formats of grep egrep fgrep commands and

in Linux there are three swords that deal with text, and what I'm going to say now is the use of the grep regular expression, which is just a notation, as long as the tool supports this notation, The tool can then handle the string of regular expressions. vi

vertical delimiter is used to select a or E instead of GRA and EY), "(grand)? Father" matches father and grandfather (the scope is experienced here?). Matches the contents of the parentheses as a whole).Iv. Grammar (part)There are many different styles of regular expressions, and here are some common regular expression matching rules for Perl and Python programm

line of filesFiles that can be trimmed by cut are generally text documents with a certain structure or format;Cut OPTION ... [FILE] ...-D,--delimiter=delim: Specifies the delimiter to be relied upon when the pruning operation is implemented, by default a white-space character-F,--fields=list: Specifies the number of the field according to the defined delimiterHow to use address delimitation:#: Select a single field to be specified#,#: Discrete number of individual fields that are specified#-#:

times up to N times, less than the base regular expression curly bracesAnchor character:\Group:(): No need to add \ support \1,\2,\3,...Or:|:or orEg:a|b A or BEg:c|cat==c or cat (not cat or cat)grep: Searches for text according to the pattern and displays lines of text that conform to the pattern. a command that uses a basic

/wKioL1RyBW6gyoowAAENihiIgQE185.jpg "alt=" Wkiol1rybw6gyoowaaenihiigqe185.jpg "/>5. Find one or two digits in the/etc/passwd file;650) this.width=650; "title=" QQ picture 20141123222739.png "style=" Float:none; "src=" http://s3.51cto.com/wyfs02/M01/53/D7 /wkiom1rybplhrb48aamxu-qfgas665.jpg "alt=" Wkiom1rybplhrb48aamxu-qfgas665.jpg "/>6, displays the line that starts with at least one whitespace character in/boot/grub/grub.conf;650) this.width=650; "Width=" 857 "height=" 131 "title=" QQ picture 2

A), the three major text processing of Linux grep:grep (Global search REgular expression and print out of the line, fully search for regular expressions and print them out): After giving a list of files or standard output, grep searches for text that matches one or more

Grep (Global Regular Expression version) allows Pattern searches for text files. If the matching mode is found, grep prints all rows containing the mode. Grep supports basic regular expressions and its extension set.

GrepIntroductionOne of the Three Musketeers of the Linux text processing, the File filtering tool (the other two musketeers for sed: Text Editing Tool,awk: Text Report Generator) owned, according to user-specified "mode" Matches the target text line by row, and prints the function of the matching line. UseGrep can also use regular expression characters in additio