grep vs egrep

Grep:the Three Musketeers of text processing on Linux1 grep: Text filter (Pattern: pattern) tool; *(grep, Egrep, Fgrep)2sed:stream Editor, text Editing tool;3 awk:linux implementation gawk, Text Report Generator;Grep:global search REgular expression and Print out of the line.Function: Text Search tool, according to user-specified "mode" to match the target text l

Grep, egrep, and fgrep for basic regular expressions and text processing tools Grep (Global Search Regular Expression and print out the line global search Regular Expression and print out the rows) is a powerful text search tool, the commands of egrep and fgrep are only slightly different from those of

) followed by a parenthesisGREP-E-O "[_[:alnum:]]+\ (\)"/etc/rc.d/init.d/functionsUse the echo command to output an absolute path, using Egrep to remove the base nameecho/etc/sysconfig/| GREP-E-O "[^/]+/?$"Find the value between 1-255 in the ifconfig command resultIfconfig | GREP-E-O "\Find all IPV4 addresses in the ifconfig command resultIfconfig |

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 regular expressions in lin

Tags: class number highlighting Roo postfix understanding direct. com LoginI. OverviewRegular expressions are the knowledge that is often needed in operational operations. File lookups, log parsing, rewrite rules, shell scripts, and so on, all require the knowledge of regular expressions. So what is a regular expression? My understanding is to find or replace the string you need according to certain rules, which is a regular expression, exactly, it is a rule. There are many commands to use regul

I. Introduction Grep is used to display the part.) match the rows in string format. Family: grep egrep fgrp Ii. How to Use grep Usage: grep [options] PATTERN file .. Options: -I case-insensitive -- Color Matching highlighted -O: only show Matching Parts -N: displays the mat

What is the difference between an extended regular expression and a regular expression when egrep or Grep-e uses an extended regular expression for text matching compared to grep?1 Basic Regular Expressions:Character Matching:.: Any single character[]: A single character in a character set such as [0-9] means any number of digits[^]: a single character that is no

"Reprinted from" http://blog.csdn.net/homking/article/details/6000711 Egrep equivalent to Grep-e Fgrep equivalent to Grep-f GREP-E xxx-e yyy can specify multiple conditions and can contain- Grep-a 3 print matching line and match line first 3 lines

Detailed description of grep, egrep, and fgrep usage of text search commands I. Learning Objectives Understand and be familiar with grep, egrep, and fgrep commands. Ii. Learning Content 1. Meaning and usage format of grep, egrep,

/meminfo For example, if the default shell is not bash # Grep-V "bash $"/etc/passwd | cut-D:-F1 For example, retrieve the user whose default shell is Bash and whose ID is the largest # Grep "bash $"/etc/passwd | sort-n-t:-K3 | tail-1 | cut-D:-F1 For example, the/etc/rc. d/rc. sysinit file starts with #, followed by at least one blank character, and then contains at least one non-blank line. #

' # ' grep-v ' ^# ' 1.txtRemove all empty lines and lines beginning with ' # ' grep-v ' ^$ ' 1.txt|grep-v ' ^# 'filter out lines that begin with the English alphabet grep ' ^[a-za-z] ' 1.txtfilter out lines that start with a non-digit grep ' ^[^0-9] ' 1.txtfilter any one or

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/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

, ...Features that increase compared to basic regular expressions| : ORA|b: Indicates a or bC|cat: Indicates C or cat(C|C) at: Indicates Cat or catUsing the example650) this.width=650; "src=" Http://s5.51cto.com/wyfs02/M00/7D/04/wKiom1bedyriKT60AAArB_vE_Ds116.png "title=" Grep23.png "alt=" Wkiom1bedyrikt60aaarb_ve_ds116.png "/>Egrep: Support for grep commands using extended regular expressions, equivalent t

grep (Global search regular RE) is a powerful text search tool that only uses basic regular expressions to search for text and prints matching lines.grep is a common and commonly used command, and its main function is to compare string data and then print out strings that match the user's needs, but the idea is that when grep looks for a string in the data, the data is filtered in the "Whole row" unit.Examp

Grep nobody/etc/passwd display rows with nobody characters in/etc/passwd, case sensitive Grep-I nobody/etc/passwd real-world/etc/passwd rows with nobody characters, case insensitive Grep-V nobody/etc/passwd rows that do not contain the nobody Grep-N nobody/etc/passwd: displays the row containing the nobody and the r

; # Cut-D:-F7/etc/passwd | sort-u 2. Extended Regular Expression Egrep: uses an extended regular expression to construct the mode, which is equivalent to grep-e. Character match: .: Any single character []: Any single character in the specified range [^]: Any single character out of the specified range Matching times: *: Match any character before it; ? : Match the first character 0 or 1 time; +: Match th

An expression Meaning C Any non-special character c that matches itself \c Remove any special meaning of character C ^ Header $ End of Line . Any single character [...] ... Any character in a character, a range like a-Z is legal [^...] Not... Any single character in the \ n Characters matching the nth \ (... \) (in

that are matched during a specific match, can be memorized by grep (stored in the built-in variables, these variables are \1,\2,... ), so that it can also be referenced\1: Reference, from left to right in a pattern, matched by the first opening parenthesis and the pattern in the right parenthesis corresponding to it\2: Reference, from left to right in a pattern, matched by the second opening parenthesis and the pattern in the right parenthesis corres

contain numbers:grep ' [0-9] '/etc/inittabFilter out all rows that do not contain numbers:Grep-v ' [0-9] '/etc/inittabRemove all lines that begin with ' # ':Grep-v ' ^# '/etc/inittabRemove all empty lines and lines that begin with ' # ':Grep-v ' ^# '/etc/crontab |grep-v ' ^$ 'How to print a line that does not start with the English lettergrep ' ^[^a-za-z] ' test