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

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Why does my grep expression need to use $'string' to match tab characters?

If you take this code: echo -e '\t\t\tString' | grep '^[\t]*String' the result is blank because it doesn't match, yet this: echo -e '\t\t\tString' | grep $'^[\t]*String' works. I swear that I ...
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58 views

Extracting just a single group from a regular expression

I am trying to get a list of numbers from some hacked-together log files using zgrep. So, I am using: zgrep -ie "total time: .* ms" * This returns the whole line that I care about. I'd just like ...
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1answer
3k views

Get all regex matches between two patterns and print them to file

I've got a file with a bunch of long lines. I'd like to grab every group between two patterns and print them to a new file, one match per line. I could manage to do this with Python, but I'd prefer ...
3
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3answers
210 views

What does . match?

In working with regular expressions, I have been told that a dot character . will match everything. Except for newlines \n. Are there any other exceptions? What about the NUL character \0, or the ...
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1answer
688 views

Regex : how to verify that there are 13 greek letters with an odd number of consonants

Another regex that I can't seem to crack :( I tried with egrep '([qwrtzpsdfghjklxcvbnmy]{1})|([qwrtzpsdfghjklxcvbnmy]{3})|([qwrtzpsdfghjklxcvbnmy]{5})|([qwrtzpsdfghjklxcvbnmy]{7})' greek.txt ...
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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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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 ...
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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 ...
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1answer
1k 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 ...
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1answer
247 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 ...
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1answer
131 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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279 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 ...
3
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1answer
243 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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1answer
1k 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
786 views

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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1answer
23 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. ...
3
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1answer
140 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 ...
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1answer
2k views

lftp exclude syntax confusion

I am confused with the syntax description given for lftp from their website: -x RX, --exclude=RX exclude matching files -X GP, --exclude-glob=GP exclude matching files How ...
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1answer
320 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 ...
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1answer
2k views

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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How can I exclude a string using a regular expression?

I have this file named test: http://edge.sharethis.com http://edge.sharethis.com https://timetosa.com http://timetosa.com https://webtest.es holahttp.com timetosa I want a expression that excludes ...
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179 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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116 views

Parsing Log Files with sed -e. Need to count unique class names

I have a file, let's call it filename.log, in it I have something like this (2014-11-18 14:09:21,766), , xxxxxx.local, EventSystem, DEBUG FtpsFile delay secs is 5 [pool-3-thread-7] (2014-11-18 ...
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536 views

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
3k 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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2answers
976 views

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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1answer
296 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 ...
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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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4answers
517 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 ...
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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, ...
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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 ...
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Can tr work with regex?

I have a file like this: AAAA BBBB CCCC DDDD etc Words in separate lines. I want to add them quotes using tr. So I tried the following: 1) To add a quote in the start of each word ...
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2answers
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How to find files with a certain subpath?

I need to find all xml-files that are placed in folders named config. Also config must be somewhere under a folder named trunk. For example, I am interested in all files like below: ...
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Remove backslashes from a text file

I have Input: NISHA =\455 Output: NISHA = 455 I want to remove \ from output. I tried to use command sed "s/[\]//g" P but it is not working and it flags an error: character found ...
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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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133 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 ...
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Extract IP address from a string

The Linux host command returns: hostA.domain.com has address xx.xxx.xxx.xx How do I get just the IP address and put it in the $ipaddr variable? open(FILE, "hostlist.txt") or die("Unable to open ...
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Why don't I need to escape a character class in sed but I need to escape the rest?

I am confused with sed. I had a file with the following contents: [ 2014/02/10 14:45:15 | INFO ] Saving data for customer: 273667 [ 2014/02/10 14:45:15 | INFO ] Saving data for customer: ...
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925 views

SED change only start of line and preserve end of line

Basically I have a situation where I frequently need to modify my hosts file to access different servers at my workplace. In an attempt to automate the process. I've been trying to use sed to make the ...
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3answers
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Pulling out keywords using standard command line utilities?

As an example, this is the pronunciation of "when" according to Wiktionary. enPR, IPA and X-SAMPA are different schemes for showing pronunciations. when:* {{a|US}} {{enPR|wĕn|hwĕn}}, ...
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3answers
680 views

Find word in sentence with Bourne Shell (sh)

I'm trying to determine if a particular word appears in a sentence using Bourne Shell (sh). For example: #!/bin/bash INPUT='Lorem ipsum dolor sit amet.' if [[ "$INPUT" == *dolor* ]] then echo ...
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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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457 views

Regex doesn't work with grep

I have a string like this TEST="/dev/sda1 on /media/sda1 type vfat (rw,relatime,fmask=0000,dmask=0000,allow_utime=0022,codepage=cp437,iocharset=iso8859-1,quiet)" (Result from mount | grep sda1) ...
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Understanding -regex with GNU find

Background I have what I think should be a simple case. I want to find all files with "cisco" in the name and do something with those files (via xargs). Finding files with ls Before I use xargs, ...
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Extract substring using regular expression on a Unix file

I have file with below contents . /ABC/RTE/AD_900_VOP_123/OPP /ABC/RTE/TRE/AD_900_VOP_145/BBB /ABC/RTE/AN_900_VFP_124/FBF /ABC/RTE/HD_900_FOP_153/WEW /ABD/RDV/AD_900_VOP_123/OPP ...
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358 views

awk, sed, grep, perl… which to print out in this case?

I have this syntax in a file (http response times from analog): <thead><tr><th class="x">seconds</th><th class="R">reqs</th><th ...
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522 views

changing pattern by removing spaces?

file : hi hello,new york, , ,brazil site ,brazil january,month is feb , , ,indiana jones task: delete all horizontal space (spaces and tab) between any two comas (like , ,) if ...
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439 views

Detect pattern repetition in a file

I want to make sure a file follows the following pattern: ... ... ... foo ... foo_KO ... ... ... bar ... ... ... ... bar_KO ... The file is extremely long, so, in other words, I want to make sure ...
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Extract substrings from each line. These substrings are in comma separated, “name=value” format

I have lines in a file that are comma separated. There are no column headers, it's mostly comma separated 'name=value' pairs. Here is some test data: ...
2
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438 views

bash - extract filenames from html file containing multiple links

I have downloaded an html file autogenerated by a script on a webpage. The file contains multiple links, including links to images I am trying to extract the full names of the images, for example ...