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

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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]|[-])+$/\\t`get_addr.py -1`/" /path/to/file.ext sed -E "s/\\t([A-Za-z]|[-])+$/\\...
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366 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 ...
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1answer
2k views

How to perform a multiline grep across multiple files?

I'm trying to grab this pattern wherever it occurs in multiple log files (Note:these patterns can vary greatly in size, i.e. the amount of Blahs): Found an txt File Blah Blah 10019874 ...
3
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1answer
391 views

pcregrep newline lookbehind assertion bug?

Attempting to use pcregrep to print the first line after a blank line. For example, contents of file first line second line I need second line to be printed. Here are a few tests using the same ...
3
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1answer
262 views

Merging text files based on their filename

I have hundred of files with the following format: 2013_01_19_xyxyxyx.txt 2013_01_19_xyxyxyx.txt 2014_03_21_xyxyxyx.txt 2014_03_21_zxzxzxz.txt 2014_03_22_abababa.txt 2014_03_22_cbcbcbc.txt etc. I ...
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2answers
622 views

Replacing 3 or more digits with equivalent number of *

I want to replace any 3 or more digit string in a text file with equivalent number of *.For example: abc-1234-45 --> abc-****-45 echo "abc-1234-45" | sed 's/[0-9]\{3,\}/*/' I tried this but it only ...
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1answer
399 views

Expanding comma-separated list into separate lines

I have a file with some data in this form: Prefix text: First Name, Second Name, Third-- The prefix differs by line. The number of names varies from one to several. The suffix (-- in the example) ...
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2answers
2k views

Rename file in Mac OS Terminal using Regex

Hundreds of images need to be renamed with a terminal command using regex on MacOS 10.9 Mavericks. The files are named this way: 0045AW489R3T(IPCAM)_0_20131124101245_931.jpg 0021DF025C8E(IPCAM)...
3
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1answer
2k views

How to insert both vimscript variable and string into vim search and replace

I've only just found out about Vimscript's existence as of today, so forgive me if this question is more basic than it seems, but I've been struggling to find an answer to this question for the better ...
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2answers
932 views

Parsing through log file and printing out regex backreferences

I want to parse my /var/log/maillog to print out the email addresses in from=<> and to=<> (mainly to do a quick check for false positives in the DNS RBLs that I've configured) A maillog ...
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Using grep/sed/awk to classify log file entries

I need to process a very large log file with many lines in different formats. My goal is to extract unique line entries who have the same starting pattern, e.g. '^2011-02-21.*MyKeyword.*Error', ...
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51 views

Using 'rename' & regex to edit filenames

I'm new to regular expression, and am trying to use regex to rename some files. I am using rename (this one) to rename said files. Below is an example command. $ rename -n 's/\(feat.//' *.mp3 (-n ...
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1answer
74 views

How to optimize 'grep'-and-save?

I want to know on which node my calculations were running on our cluster in case the node crashes and I get no files back to know on which node I have to search. For that case I wrote a little script ...
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3answers
91 views

backreferences in `rename` regex

I have A LOT of files named "bar_foo.txt" in a directory, and I'd like to rename them to "foo_bar.txt" instead. In sed and vim the regex to to this would be something like 's/\(bar\)_\(foo\)/\2_\1/g',...
3
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1answer
103 views

Regular Expression to match (not x) and y (!x & y)

I received a desktop day-to-day calendar with puzzles. One such puzzle was deciphering a quote where the letters were substituted with symbols. I used some RegExs to find longer words, then used the ...
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2answers
137 views

Find Files not an regex whitelist

I have a huge Folder with thousands of Files. Some Files have some Characters in it, which are not allowed. (UTF-8 signs) So I have a white list of allowed characters and a beginning of a bash-script ...
3
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1answer
89 views

Find repository names from gitolite info output

How do I extract the names from the gitolite info command output, for further piping into a script? I'm writing a migration script to migrate all my repositories from gitolite to a Gitlab server. ...
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1answer
2k views

How to search mail logs effectively with `RegEx`

I was looking for some advice and examples on searching mail log effectively Suppose situation is like this -------- Forwarded Message -------- Subject: Fwd: Re: Notice of Allowance Date: Fri, 13 ...
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1answer
529 views

How do back-references match in sed?

I found a one-line sed command on this site which removes duplicate entries in $PATH. There is one concept that I can't get my mind around. It uses saved matches in the match section to detect the ...
3
votes
1answer
840 views

Aptitude regex engine

I was trying to lookup the versions of libdb in the debian archives with something like that: $ aptitude search '~S~ndev$(~nlibdb~(\d~|-~)!~v~rnative)' which didn't work as expected so I changed ...
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2answers
776 views

Parse apache logs to exclude IP ranges

I need to look for some requests in a huge pile of apache logs. My only requirement is this: I need to only view the requests coming from any IP address that is NOT included in a list of 50 IP ranges ...
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1answer
480 views

Character classes: construct my own

I want to construct my own character class in a script, then modify (and use) it, for example: [:myclass:] contains a, *, \n (as linefeed) and [WHITESPACE]. I want to add all characters to [:myclass:...
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How to block the Google Analytics Script using Privoxy

Related subject: Privoxy: blocking twitter, facebook and google outside of their domains + HTTPS Never mind what rule I am adding to the default.filter file, I don't make it to block these scripts. &...
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470 views

Coloring tail output with perl

tail -f logfile.log | perl -pe 's/.*foo*/\e[1;41m$&\e[0m/g' will color all the lines containing the pattern "foo" in the logfile.log file. How can I make use of this in order to highlight ...
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How can I get the first column of a 300GB txt file?

let me first explain my problem in detail. It's actually pretty simple. I have a huge .txt file, 300GB to be more preciese, and I would like to put all the distinct strings from the first column, that ...
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4answers
4k views

Change filename from lowercase to uppercase recursively

I have 1,000,000 files in some folders and subfolders. I want to rename them from lowercase to uppercase using shell commands. I don't want to modify the extension. only filename part. I have found ...
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Wget - Mirroring a full website with requisites on differents hosts

I am trying to make a full static copy of a wordpress website with wget to be browsed without any network connection (all links and images must be converted). The different requisites for the pages (...
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309 views

Ex and Vi: buffers and regexes

I want to put regex matches to buffer but cannot get even simpler example y :.put myNewBuffer return msg [line] [put] [buffer] working ie how to put something to buffer? So to regular expressions ...
3
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2answers
69 views

Replace only on the first matching line with sed

Using BSD sed (no GNU extensions), how can I perform an operation similar to the example provided below, but where instead of the line number, the replacement is performed on the first line in which a ...
3
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223 views

What types of regex DO support (e.g.) negative lookbehind?

Bash on GNU: I am using a collection of find commands, most of which employ -regex to do their matching. Each time I try a different feature in my regex I have to cycle through the values for -...
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How to use regrex with AWK for string replacement in this example? [duplicate]

Possible Duplicate: How to use regrex with AWK for string replacement in this example? Suppose there is some text from a file: (bookmarks ("Chapter 1 Introduction 1" "#1" ("1.1 Problem ...
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5answers
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(Mac Terminal) sed to parse JSON … what am I doing wrong?

In Mac Terminal, I'm trying to parse the "name" out of this JSON response: {"created_at":"2012-08-27T20:04:27Z","deleted_at":null,"id":21462840,"item_type":"video","name":"CastingBy-v12 mixed....
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4answers
720 views

Why does the grep command ignore the period in the search string?

The command that I am using: find . -type f -name "*.sql" -exec grep -i -l 'schema_name.' {} + What I want to search is all the files which contain schema_name.. But the find command is ignoring ...
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4answers
340 views

Replace regex match with string containing match

I have a file with text as Afghanistan=+93 Albania=+355 Algeria=+213 American Samoa=+1 Andorra=+376 Angola=+244 It has all the country list and its dialing code. I want to replace: Afghanistan=+...
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5answers
4k views

remove leading string in bash

I try getting this sed command to work. I have a string like rev00000010 and I only want the last number, 10 in that case. I have tried this: TEST='rev00000010' echo "$TEST" | sed '/^[[:alpha:]][0]...
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5answers
586 views

ls | grep works doesn't work with ls --color

I'm trying to list all hidden dirs with the following command ls -lhAF1 | grep -E '^d.*[0-9]{2}:[0-9]{2} \.' which works perfectly fine Explanation for Regex: I'm trying to get all rows that ...
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5answers
329 views

Duplicate lines and make them unique?

I have the following structure of text lines: 3923 001 L05 LV,L05 RM 3923 002 L12 RA,L12 LA 3923 003 I06 ALL 3923 004 G04 RV,Z09 ALL but i would need this: 3923 001 L05 LV 3923 001 ...
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3answers
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sed, grep, or tr command that returns only Latin characters from a UTF-8 file

I am working with the text of the 300 tang poems, which unfortunately is a single file containing both Chinese and English. Since I am interested in 'extracting' the English, I hope to use sed, grep,...
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3answers
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sed one-liner to delete any line that begins with a digit

Pretend I am working with this file. The beginning of the first visible line is obscured, so ignore that. 43 is the beginning of the next line, and that line would be deleted. The next line (which ...
2
votes
5answers
677 views

Replace characters in user part of email address

I have a list that looks like this: user-name@domain.example user.name@domain.example user_name@domain.example ... I would like to replace any occurence of a dot in the username part. So that: ...
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votes
6answers
490 views

Extracting IP address from a text and store it in a variable

I have a text file named abd shown below. 48878 128.206.6.136 34782 128.206.6.137 12817 23.234.22.106 I want to extract only IP address from the text and store it in a variable and use for other ...
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votes
4answers
8k views

Match multiple regular expressions from a single file using awk

I'm trying to parse a HTML file using shell scripting. There are 4 different regular expressions that i need to catch: name= , age= , class= , marks=. Using grep "name=\|age=\|class=\|marks=" ...
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1answer
330 views

shell: The =~ operator does not work as expected

Consider the following script: #! /bin/bash line="confusing" if [[ $line =~ [[:lower:]]* ]] then echo "matches!" else echo "does not match." fi While the above produce the expected result,...
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Renaming using terminal and regexp to remove leading numbers from filenames

I want the following files to be renamed removing the sequence numbers. 01 X.mp3 to X.mp3 02 Add Me In.mp3 to Add Me In.mp3 I am trying with the below rename command. rename -v -n 's/^\d+\s*([a-z]+...
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votes
4answers
2k views

SED command not replacing (working regex)

I'm trying to replace in one of my projects all mysql to mysqli, with their parameters. To do so, I'm searching for all files with mysql in my folder recursively and replacing it with mysqli. Ex: ...
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2answers
234 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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2answers
173 views

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

What does this regex do? <!--.*?-->
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3answers
159 views

Apply item replacement inside enumerate in Perl regex?

Data 7. Masi is the same as \begin{enumerate} A B ABC ha lorem \end{enumerate} 1. ABC is \begin{enumerate} P B Lorem maam \end{enumerate} which I want to be 7. Masi is the same as \begin{...
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2answers
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Differing outputs of the commands “ls .*” and “ls *.”

The command ls .* when run gives as output the following : All the files in the current directory starting with a . (hidden files) All the files in the hidden directories present in the ...
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3answers
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Print lines where first field has only four characters using regex in awk?

John Goldenrod:(916) 348-4278:250:100:175 Chet Main:(510) 548-5258:50:95:135 Tom Savage:(408) 926-3456:250:168:200 Elizabeth Stachelin:(916) 440-1763:175:75:300 output should contain the lines ...