Regular expressions are a means of matching a pattern of characters within a string.

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how to replace a sed/perl expression (change and print only matched line) with a python expression?

I have asked this question to learn how perl could replace sed. Now I want to know how the following commands (which do the same thing) would look like for python: sed -n ...
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Simple way to extract value from HTML

I have a very simple html file with a value inside. Value is 57 in this case. <eta version="1.0"><value uri="/user/var/48/10391/0/0/12528" strValue="57" unit="%" decPlaces="0" ...
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How can I use sed to remove the first paragraph of the file?

So the paragraph is defined by having a empty line at the end. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nunc et nisi tristique, facilisis orci nec, pellentesque tortor. ...
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Bash Combine Replacement and Sub String Extraction in One Step

For a string in this format: ./my-site.sub.domain.com I would like to remove the .,-, and /, and trim the remainder to 16 characters: mysitesubdomainc I've done this ...
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Find and change certain LaTeX coding in vim, using regular expressions?

How can I change the following LaTeX coding: \cite{1,3-7,9} to \cite{1,3,4,5,6,7,9} in vim? I would prefer to use regular expressions.
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Pattern repetition and regexp

Take the pattern [UGLER]* Can the string UUG match against it? I mean to say, is repetition allowed?
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rsync exclude based on file size?

Is it possible to exclude files in rsync over a certain size (e.g. over 250 MB)? And what if I also want to exclude hidden files? How would I exclude all hidden files or directories (those that ...
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How to print only the first match with grep

I'm trying to grep username: users | grep "^\b\w*\b" -P How can I get it to only show the first match with grep?
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Weird zsh grep -P behaviour

I connect to server with PuTTY from Windows. I have a long yet not touched (I suppose) by hands of local admin config: $ cat /opt/jira/.subversion/config ... ### must be enabled, which is ...
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sed pattern matching

I recently asked someone at work about how to take the output of ipcs -qa and make it space delimited, so I can parse it/store it in the database for monitoring. He gave me this: ipcs -qa | sed 's/ [ ...
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What does this egrep command do?

What does this egrep command do? egrep '[^A-M][0-9]+' /etc/passwd So far I think it searches for any file in /etc/passwd that starts with A-M and includes the number(s) 0-9. Is that right?
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Pattern matching [duplicate]

I am trying to follow Bash Cookbook to learn about Bash Scripting. I am on example 6.8 Testing with Regular Expression. I have the following script: #!/usr/bin/env bash # cookbook filename: ...
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regular expression : with a variable

arrFormat=( jpg jpeg bmp tiff png ) varExtension="jpg" for elem in "${arrFormat[@]}" do   echo "${elem}"   # do something on $elem # done #for i in $( find -E . -iregex '.*\.($arrFormat)' ) ; do ...
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How extract under linux some capturing groups using command line in a php/preg fashion?

Given in linux environment exists lot of packages for manipulating strings (grep, awk, sed, ...), I would like a software to extract a capturing group in a php/preg like syntax. Maybe the most close ...
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How do I replace this pattern with a newline inside it? [duplicate]

If I have a text file with this content: someline <!--\ file first read on 2015/01/11 And I want to delete <!--\ and everything until what comes after "on", how do I do it? The ...
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regex matching and substring extraction

I have these files, manually created by many different people are coming in. Formatting, although following a certain rule, is not uniform. think of these three lines below ...
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Fast field extraction with grep

The problem I have a 32M lines file with the following format token^Iname^Iurl$ where ^I is the tab escape sequence, and $ is the end-of-line. I need to get the url corresponding to not more than ...
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How can I use the environment variables inside a regular expression in awk?

#!/bin/sh ALTER="1153" NAME="aio" for i in $(ps -eo pid,etime,comm | \ awk -v alt="$ALTER" -v name="$NAME" '$2~/[^0-alt]-/ && $3~/name/{print$1} '); do echo $i done
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Remove last comma within a pattern

If I have the following text within a file (somefile.txt): CREATE TABLE "table_name" ( "id" int(11) unsigned NOT NULL, "some_field" varchar(10), ); CREATE TABLE "another_table" ( "id" ...
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Delete everything before “/” on every line

I am trying to delete certain text that appears before / on every line. I have something like: testing.db.com/7fad416d-f2b3-4259-b98d-2449957a3123 ...
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what is meant by “^$1” in shell script?

#!/bin/sh #emp3.sh: using if and else # if grep "^$1" /etc/passwd 2>dev/null then echo "pattern found - job over" else echo "pattern not found" fi in the above programme what is "^$1" and ...
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Ack regex on filenames

According to this thread: Q: My understanding is that ack uses Perl-derivative regular expressions, is that correct? A: Yes. In fact, ack is written in Perl and just forwards the expressions ...
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Replace a string and replace it with a part of itself

I am cleaning up my data that is stored in text files. Each line starts with a category label followed by the actual data that I want to clean up. There are many text files in different subfolders, so ...
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What does the dot in regex “^[A-Za-z]{2}[1-9]{2}.*” do?

I am very new with regexp. I would like to know the pattern defined by this regexp : ^[A-Za-z]{2}[1-9]{2}.* It starts with 2 alphabetic characters then 2 numeric characters then a . and * which is ...
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use search result in replace statement with vim substitute

I know this is gonna be a stupid question, but I've tried here, google and the official documentation. I've got a file with a whole heap of words of the form 'foo' and i want to change them to ...
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What does this regex mean?

I was working on the conversion of Unix newline to Windows newline. I tried to unix2dos but it gave me some binary error, so I looked it up and stumbled upon this regex sed 's/$'"/`echo \\\r`/" ...
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using simple regex quantifier expression in grep

Does anyone know why ls | xargs -n 1 basename | grep -E '[0-9]{1}' does not only show occurrences of a single digit between 0-9? For example if I have: touch 1 touch 22 touch 333 touch test_file ...
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Grep and regex, Why does the following return only a specific portion?

Why in the following: echo this is a line. | grep -o -E "[a-z]+\." The result is line. and not this is a line.? There is no word boundary or any other restriction on the regex.
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Why is this Bash command using regex not replacing my brackets?

I have this command to go through all my files in my Music directory, and all subdirectories, and replace any square brackets in the file name with rounded brackets: find /home/Music/ -depth -name "* ...
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Regular expressions help

what the different between these two regex expression ? AB\{4\} and (AB)\{4\} for the first expression I think that it repeat B 4 times, then for second expression it repeats AB 4 times. When I ...
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349 views

Match a simple Regex

I need to match this: (tt\d{1,10}) in a file with the file ending txt. I have tried grep and ack-grep but without results. ack-grep -G \.txt$ -g "(tt\d{1,10})"
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How to find and replace files contents that match a pattern?

Suppose we have a folder named Project. I would like find each file in the folder that contains the pattern &$ at the function call. For example should replace: AnyFunction(&$arg); with ...
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pattern search and display the last occuring pattern?

I have a log file containing startup and shutdown times for everday. I want to see the last pattern for startup and shutdown (which is located at the end of the file being updated everyday). Also I ...
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Processing control characters

I have a log file which contains a bunch of non visible control characters such as hex \u0003. I would like to replace this using something like SED, but can't get the first part of the regex to ...
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Strange “apt-get purge” behaviour with regEx

I'm running Debian (jessie) and following this question, I followed the first answer suggestion to install that packages running sudo apt-get install gtk2-engines-* gtk3-engines* That did not ...
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Finding and removing words beginning / ending with numbers

I have a large file (>10000 lines) that contains one word per line, with a newline character after each word. The words contain no spaces. I'd like to list (or even better, output to a new file) any ...
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How to sort blocks of lines with a specific line from the block?

I have a file with the data like this BEGIN hello2 5 world1 END BEGIN hello4 2 world5 END BEGIN hello6 4 END I want to sort the lines in the following manner based on the number inside the block. ...
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How to grep all words starting with digit?

I am wondering how to grep all words starting with digit. So far, I have made this: egrep "^[[:digit:]]" tst But it prints me just a lines starting with digit. Thanks in advance with help.
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Help with regular expression in grep

someone can explain me why this regexp doesn't work in grep? ls -la ./ | grep -E '^d.*\<\..*\>$' In my (wrong) opinion this have to show me the line of the directory with a name that start ...
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How to make + work in sed's regexps on FreeBSD?

Consider the following typescript: $ freebsd-version 10.0-RELEASE-p5 $ echo ' found' | sed -n '/[[:blank:]]\+/p' $ echo ' found' | grep '[[:blank:]]\+' found When I do this on Arch Linux with GNU ...
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Sed replace portions of lines not beginning with http://

I'm getting stuck with sed.. I'm trying to prefix links in an html file with a / when they don't start with http.. I'm aware this is possibly not the best way to go about this but I'm just after a ...
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parse credentials from PHP configuration file

I'd like to write bash script to parse data from a configuration file. I searched for this but without finding something I could modify to suit my needs. Joomla! config file: public $access = ...
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How to search multiple search patterns from a file with grep

If I search for multiple search strings in grep : usually just do: grep "search1\|search2" somefolder/*.txt but, what if I have 100 or more search strings? Can I say like this: grep ...
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How to use sed to replace keys in a file using a regex?

I would like to modify a file to replace keys, suppose these keys are in the file as: 42NM 52NM 23NO XNNM I would like to replace anything with NM, with the word "Okay". 1 #!bin/bash/ 2 3 if [ ...
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To Regex Pandoc Tables

Minimum Data to regex \documentclass{article} \begin{document} ------------------------------------------------------------- A B C D Header Aligned Aligned ...
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sed: problem while replacing string using wildcard

I am trying to replace a string using the following command: sed -e "s/\<$5\>/$6/g" "$2/$1" > "$4/$3" $5-> "hostname=*" $6-> "hostname=int1" $2/$1-> "source file path" $4/$3-> ...
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Why does regex with \\$\{ work with egrep, but not with sed?

Given a text like this ./RFF_09 -f${FILE} -c${COND} inside a file, this egrep command will correctly match: egrep './RFF(.*) (.*)-c\\$\{COND\}' file but this sed command will not sed -n ...
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How to express all files/directories at the extra -exec option of `find` command?

I have a task to copy all files from multiple directories with special names to a target directory. So I build this directory to test my command. The test directory tree looks like: . ├── dir1 │   ...
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Why doesn't my regex work in bash “if”? [duplicate]

Here is my code: if [ -f /Applications/xml[0-9].pl ] I also tried with -f =~ and double brackets but none seem to work. I first though that the regex might be faulty but I tried this. echo h1 | ...
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“bad flag in substitute command: '{” while replacing a string with sed from one file to another file

I am trying to replace strings found in File1 with strings in File2 File1 <IMG SRC="/Repository/GetImage.dll?baseHref=Orange/2011/03/27&amp;EntityID=Ad12911&amp;imgExtension=" /> ...