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

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perl rename: Prepending something to a set of file names across subdirectories

Although perl's rename tool has become an invaluable companion for my daily work, there are still some quirks that make work more difficult - especially when files are not in current work directory. ...
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394 views

Use sed to delete all but a certain pattern

How do I get just the link part in the http-source of a link? I have <a href="http://unix.stackexchange.com/users/20661/">Unix &amp; Linux and would like to get just ...
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43 views

SMTP log anonymize script

I have a SMTP log with records in the format below: 6,222.3.4.5,3040,100.2.3.4,25,UNKNOWN,0,1,……,9337bc-929a-34c0-29a8-b3a89c834b29 ,protocol,SMTP ,745663746,STATUS-COMPLETE ,VALID ...
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Regular Expression for Mixed cased words

I want a regular expression that will help me identify if a certain pattern is present as a mixed case in a sentence or not. Say: Fox juMPed the rock Now, I want to find that if the pattern ...
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1answer
655 views

How to escape unbalanced brackets or slash in sed?

I'm trying to use sed, but my pattern contains [] brackets and slashes (/). I've tried quotes, but it doesn't help. How do I escape it? Examples: $ sed -i'.bak' "s/^includes[] =/;includes[] ...
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how to use regex in alias?

I want to create the alias for the command "ssh user@10.32.44.225" as 10.32.44.225 alias [0-9][0-9][0-9].[0-9][0-9][0-9].[0-9][0-9][0-9].[0-9][0-9][0-9]="ssh user@$0" I have created it, but it is ...
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0answers
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To visualise look-behind in this Regex

I am using Regexr to visualise my regexes now. I need look-behind but Javascript does not support it, example code here. The project code base seems to be dependent Javascript (NodeJS) in Github. I ...
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In VIM, replace path with slashes without using escape slashes

In vim I want to substitute a long path /a/b/f/g/d/g with another /s/g/w/d/g/r in a text file. Usually I use \/ but there are too many slashes here. Is there an easier way?
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1answer
86 views

How to nest global matches with sed?

If I do: sed 's/match/replace/g' I know that sed will substitute replace for every occurrence of match on a line. But what if...? echo "match <please dont match this?>" | sed ...
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Need .htaccess Rewrite Rule To Remove Trailing <br%20/>

I have links that for some reason have a trailing <br%20/> and I don't know where they are coming from to try and fix them. So I need a general rewrite rule to remove them so the links won't ...
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2answers
228 views

How can I remove lines matching foo but not matching bar?

Assume I want to remove the 2nd and 3rd, but not the 4th line in the following file (those which match foo but do not match bar), can I easily do this with e.g. sed? text foo some more text even more ...
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4answers
343 views

Decreasing a number with sed

I extracted the metadata of a PDF in a .txt file using pdftk, and now I am trying to decrease the BookmarkPageNumber value for each bookmark by an integer. The .txt has these lines: BookmarkBegin ...
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3answers
737 views

Remove patterns from string using bash

I'm trying to remove some patterns from a file input string (parsing file line by line). Here is a sample string: 1: (10/17 12:49:31.175) - CONSTANT ID1 - CONSTANT ID2: RAW DATA OUT > ...
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1answer
70 views

Regex for contains at least one instance of STRINGA and no instances of STRINGB

What regex will match: contains at least one instance of "1221", and no instances of "7474" i.e. matches "7777 1221 4543" but does not match "7777 1221 7474 4543" I suspect I have to use negative ...
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4answers
507 views

Regular expression using \\ vs using \

Why does grep e\\.g\\. <<< "this is an e.g. wow" and grep e\.g\. <<< "this is an e.g. wow" do the same thing? If I add a third slash, it also has the same result. BUT, once I ...
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2answers
80 views

What does this regex mean? <!--.*?-->

What does this regex do? <!--.*?-->
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1answer
381 views

Regular expression to mask credit card digits in a file

What is the most simplest way to mask all numbers but the last 4 digits of a credit card number in a file using sed. Using egrep with the following regular expression we can find numbers of Visa, ...
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96 views

Find & replace image URLs in one file from another file

I am trying to replace all the image source URLs in an HTML file from a list of URLs in a text file. File1.html <td class="MetadataRes" width="380px" colspan="2" style="border-top: 1px #336699 ...
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3answers
704 views

“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=" /> ...
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4answers
108 views

replace several comma out side one or more sets of curly braces and exception that in one or more sets of curly braces

In the text file I have multi records. Every record has multi column with comma separated, some column have one sets of curly brace and other have more than one curly brace. I need: If a comma is ...
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2answers
123 views

Regex to grep filler followed by signed float

I want to extract the last column from lines that look like: 880.952 NAV_Y uSimMarine -146.17516 The number isn't always negative, and isn't a fixed length (i.e. doesn't ...
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2answers
46 views

Match from current line until a line that doesn't match a pattern

I really tried searching but could not find anything (it's hard to know what exactly to search for). I know how to do this with sed: print from current line until the line that matches SOMETHING: ...
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1answer
227 views

Regex works in shell but not through Perl script

I'm having trouble executing a Perl script through the Unix shell using Perl's system command. I've had more complex regex commands I had to adjust accordingly to convert from Unix to Perl, and ...
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60 views

To match only innermost environment by Regex

I want to match the innermost environment of begin{question} and its corresponding end{question}. Example data \section{Takayasu arteritis} \begin{question} {You get a patient. What do you notice ...
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1answer
165 views

To write this Pseudocode with Regex

I am doing a Makefile which I run regularly by Crontab every day at 0230 crontab -e; 30 2 * * * /bin/thePseudocode Python-like Pseudocode directories = ["Cardiology", "Rheumatology", "Surgery"] ...
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113 views

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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201 views

Replace using vim - Replace a pattern […] by a string

I have a file containing lines in below e.g. format - [foo@host.com, bar@host.com], Payment processed - 23499, params = {'invoice':3243} I only want the account numbers i.e. 23499. It's a number. ...
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2answers
163 views

What is the regex to validate Linux users?

When adding a new user, how is the string validated? I suppose there is a regular expression. What is that regular expression?
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440 views

Shell pattern matching vs. regular expressions occurence [duplicate]

I am relatively new to Unix, and I stumbled across one curiosity. Some shell constructs like case or find, employ pattern matching, but it is not quite regex. Other commands, like ed, sed, vi, and ...
2
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2answers
108 views

Find characters in the file

I need to find lines in the text file that have at least one x and at least two ys. I tried the following: grep -E "x.*y{2}" file.txt This method did not work. Is there another way to do it?
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grep to find words with all vowels

Using grep -E and regular expressions I need to find words containing all of a group of characters in no particular order. For instance a word containing all vowels (aeiou) however the vowels can ...
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127 views

vim replace search text by manipulated search text

This is a very simplified version of my problem. Suppose I have a text file containing several places the code 20091a or 20092a or 20093a. I'm wishing to surround all this code by the text ...
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3answers
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Yum regular expression or wildcard search?

Fedora documentation says: 5.2. Advanced Searches If you do not know the name of the package, use the search or provides options. Alternatively, use wild cards or regular expressions with ...
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3answers
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Why does [a-z] asterisk match numbers?

I have 3 directories at current path. $ls a_0db_data a_clean_0db_data a_clean_data $ls a_*_data a_0db_data: a_clean_0db_data: a_clean_data: $ls a_[a-z]*_data a_clean_0db_data: a_clean_data: I ...
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Replacing a pattern in line preceding another pattern of interest

I have a log file with many instances of statements as shown below: 14 Aug 19 16:30:11.506: <DATA> |POS|IDLE|1|01131844090|5950|$hostIp|$size |$data 20 Aug 19 16:30:12.439: <DATA> ...
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3answers
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Replacing string in all files found by grep. Can't get it to work

I'm trying to do what title says. So I find all needed files with grep: grep --include=\*.{php,ini,conf,sh} -ril -P "'([\d\w\-\_\.]+)(@domain.com)'" '/var/www_data/somepath/' Now I assume it's ...
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file(1) and magic(5) : prioritizing a result

My question follows that one: file(1) and magic(5) : describing other formats . I want to describe a FASTA sequence ( http://en.wikipedia.org/wiki/FASTA_format) It could be a DNA sequence (with only ...
3
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2answers
109 views

Extract specific set lines matching a rule

I have a large file with the logs as shown below. There are about 30000 instance of such events logged. I need to extract those lines beginning with RINGING and CLOSE (included) and which does NOT ...
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4answers
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regexp which matches all tokens independent of order

I have a quick (and hopefully simple) question about regexps. I'm trying to think of a regexp which matches all of a set of tokens irrespective of order. So for example I have a file with the names ...
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How to remove a newline character in a particular line through perl?

I want to remove a newline character in a particular line through perl one-liner command. Input: 1407233497,1407233514,bar 1407233498,1407233515,foo mingstats&fmt=n 1407233499,1407233516,foobar ...
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How can I parse my String using regular expression to get only certain number of matches? [closed]

I am currently using this following regular expression to split my String into groups. ^([a-zA-Z0-9]*)(\[([a-zA-Z0-9=]*)\]){0,1}@([a-zA-Z0-9]*)$ Pty[R=4]@ID I am getting four groups 1) Pty 2) ...
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1answer
79 views

Using sed to replace only the first two regex catches with different strings

So I'm trying to change two instances of a regex pattern to two different strings with sed like: sed -E "s/\\t([A-Za-z]|[-])+$/\\t`get_addr.py -1`/" /path/to/file.ext sed -E ...
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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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Checking if an input number is an integer

I'm trying to check if an input is an integer and I've gone over it a hundred times but don't see the error in this. Alas it does not work, it triggers the if statement for all inputs ...
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How can I “merge” patterns in a single line?

I am doing grep and sed and I get 2 lines of a file that I am interested in. How can I get these lines in a single line ending with the new line character? Now I am getting: pattern1 pattern2 ...
4
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1answer
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command: ls /etc | sort | grep d* is yielding no results but ls /etc | sort | grep p* lists entire directory

I am playing around with piping and grep tonight. I know that grep uses regex and that * means 0 or more occurrences of the preceding character. So the way I understand it is that if I do the ...
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5answers
380 views

Insert Lines after Multi-Line Regex Match

I've got an XML file I need to append to after a specific set of tags. Basically the file structure looks like this: <key>servers</key> <dict> ... Server Details ... </dict> ...
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1answer
1k views

find words with all vowels in order from a file

I have a large dictionary file with 300,000+ words in it and I'm trying to find all words with the vowels aeiou in that order and have only exactly 5 vowels. My current attempt does not seem to be ...
3
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1answer
49 views

Problem with regular expression in gawk ('\<' not working)

I am trying to get into bash a little bit. I was going through this guide but the second example in this subsection on gawk doesn't seem to work. The problem is this command: ls -l | awk ...
3
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1answer
57 views

Accept only y or yes with a one-line regular expression

I want to check if an input is y or yes (inputs in lowercase) and reject everything else What I have now is ^y[e]{'0,1'}[s]['0,1']$ But this accepts y, ye, ys, yes. I don't want ye and ys to be ...