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

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How do I match beginning/end of string in regex?

I know that there's ^ and $ but those are for the beginning and end of line, I am trying to match the beginning and end of string/word. I tried to use \b, which didn't work. For example: echo "lol ...
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3answers
264 views

How to subtract 1 from numbers matched by regular expression?

I'm trying to write a script that reduces each number in line by "1", but I'm getting all "0"s instead: awk '{a=gensub(/([0-9]+)/,"\\1","g",$0); if(a~/[0-9]+/) {gsub(/[0-9]+/,a-1,$0);} ...
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40 views

Why is this command to open man page and perform search not working? [duplicate]

This open-man-page-and-search-for-string-in-a-single-command question half covers what I'm trying to do: Instead of doing man chmod and then /a+x to jump to the first section in the chmod man ...
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297 views

Grep exact number of digits and some other characters

I'd like to parse a file containing 5 digit numbers separated by comma or dash, lines like : 12345,23456,34567-45678,12345-23456,34567 My goal is to find lines which have incorrect formatting eg. ...
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106 views

Puppet doesn't ignore whitespace

I have an entry that may or may not appear in /etc/rsyslog.conf: # Added for Kiwi *.err;*.emerg;*.alert;*.warning;*.debug;*.notice;*.crit;*.info @10.19.24.50 Since some of these servers ...
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Grep that works with overlapping patterns

I want to count the number of repeating patterns aa in a very big file. So I use the following command: grep -o "aa" ./bwt/dblp.txt | wc -l This works, except when I have a string such as aaa, ...
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Print up to (and including) the nth occurence of a pattern in a line

Let's say I have multiple lines similar to below in a file. Turbo is a cat. cats are good. cats are not dog. Coco is a black cat. cats are furry. cats are not dog. now, if want to grep all the ^.*...
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Which of the following use of anchor is correct in regex using grep?

Both of the below commands gives the same output, however which one is the correct method to use it? grep ^'\<that\>' file.txt Searches for the line which has that as the first word grep '^\&...
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29 views

string substitution using sed

I have this string for example : asddsa "ll" sadd " fsgsg" "sdafaf" "lkkx" "fsgfgsg" I want to substitute all characters inside " " with a character x. Expected output in this case should be: ...
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Simple Regex match not working

I have the data below which I am trying to parse out the tittle with each of the following RegEx, Some Entries have a (Year) or other do not. same with the database number. is seem to get different ...
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43 views

Using sed to substitute a string containing variable integers

I have a text file and want to use sed to replace the following string (including the "s): " rel="lightbox[1846]" title=" with # The numbers between [ and ] are variable and change. I want to ...
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Define a variable to awk pattern matching from bash

I am trying to grab 100 lines after the text "time: X" with X in {0,40,80,...,200}. Here is what I have so far: #!/bin/bash start=1 end=5 for i in $(seq $start $end);do j=$(($i*40)) awk '/time: ...
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4answers
669 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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Is there a way to use regex expressions to auto-fill filenames in bash?

Assuming I have a directory with files as shown: $ ls file0001.txt file0002.txt file0003.txt file0004.txt file0005.txt someotherfile.txt Lets say I want to run the following command: $ cat ...
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searching a file [closed]

I want to find in the system a file, and I know part name of it. How could I do that? I tried unsuccessfully the command: find / "*partname*" The problem is probably very easy however I cannot find ...
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103 views

Print start and end between two patterns excluding end of range [duplicate]

I want to use sed -n "/START PATTERN/,/END PATTERN/p" file.txt pattern to search in a file. file.txt content is ~keyword~, ~output~. ~1.~ ~output~. ~2.~ ~output~. ~keyword~, ~output~. ~1.~ ~output~. ...
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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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Case-insensitive search in awk

I need to search for a keyword using awk, but I want to perform a case-insensitive (non case sensitive) search. I think the best approach is to capitalize both the search term ("key word") and the ...
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Extracting library directories from a long variable

I declared a long variable containing the libraries to use during the compilation: export LIBS="-L/usr/lib -lcurl -L/lib -lhdf5 -Wl,-rpath,/lib -L/usr/lib64 -lglpk -Wl,-rpath,/usr/local/tools/vtk-6.1....
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SED Search and Replace on Linux [duplicate]

I want to change the value from 1521 to 1525 in FROM_HOST only in file gexhosts.cat: FROM_HOST db201521 TO_HOST db201521 Is there a way to do that or some work around? I would really prefer ...
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Different regex engines and syntax in unix tools like grep, find, vim, sed, aptitude etc [duplicate]

I would like to learn and use regex more. I made couple tutorials and trying use regex in everyday tasks. But I've found thing that demotivates me and slowing learning process - different syntax/...
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32 views

Perform regex search on a previously regex-matched line (one-liner)

I need to print a string which is in a unique line in a long text file. Example relevant line in file long.txt: Software version 4.0.10, 2002-03-28 The wanted string is exactly 4.0.10. The steps ...
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How to catch everything after prefix phrase with SED?

How to catch everything after prefix phrase with sed? Like here I wished to catch active/idle: $ sudo hdparm -C /dev/sda /dev/sda: drive state is: active/idle $ sudo hdparm -C /dev/sda | sed "s/\...
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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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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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Does find Command Do Match For Regexp Because Of Implementation?

In this case discussed: find (GNU findutils) 4.5.11 grep (GNU grep) 2.20 Let's say I have a directory that contains a bunch of files. I want to find the files named jtobdops02.key and jtobdops.02.cer....
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Bash group matching

I am using bash 3.1.17(1)-release and script below. It doesn't show group match for input i.e. 4fwk2_dev 2fwk5_dev echo $FWK FWK_REGEX="/(\d{1,3})fwk(\d)_dev/" if [[ $FWK =~ $FW_REGEX ]]; then ...
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sed to change dns log string format

I want to use sed to change the following text: (3)www(5)first(3)nth(6)domain(3)com(0) to: www.first.nth.domain.com Can each group between the parenthesis separators be captured and then ...
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Perl one liner to find words longer than 63 characters

I have a number of XML files containing sanskrit texts to be converted to tex. Latex has a maximum of 63 characters per word for its hyphenation to work, everything longer than that will not be ...
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pattern regex for apache rewrite rule

I have the following pattern on a few thousand lines I will like to use regex to convert to what I want RewriteRule ^/omg/deadly-venom/?$ http://www.example.com/omg/deadly-venom [L,NC,R=301] ...
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Find all folders starting with number range

How can I find all folders starting with a value in the number range 500 to 899? I just need to list them in a file. Additional informations: Maxdepth 2 Examples of folder names: ...
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Is there any text search tool preloaded with well-known regexes?

I would like to know if there is any command line tool to search text files preloaded with some well-known regexes (IP, email, date, path, url, xml tags, etc) so you could do something like: grep -A ...
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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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How to catch with RegExp first word with different first symbol in it using ed text editor

I have shell command: printf '/^PermitRootLogin/\nc\nPermitRootLogin no\n.\nw\nq\n' | ed -s /etc/ssh/sshd_config And I need catch #PermitRootLogin like PermitRootLogin but not commented paragrath ...
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List lines that consist of a single non-vowel character

I need help with listing lines that consist of a single non-vowel character. I got this: ls | grep -nv '[aeiouy]' file But this doesn't give me a single character. How do I get just a single ...
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find lines that don't end with 'rpms' with sed

I would like to find lines that do not end with 'rpms' with sed in Linux. I have tried below: sed -ne '/?!(rpms$)/p' But unfortunately, it is not correct.
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Add quotes and new delimiter around space delimited words

I have the following string y10_zcis y10_nom y10_infl y20_zcis y20_infl y30_zcis I would like to transform this to "y10_zcis", "y10_nom", "y10_infl", "y20_zcis", "y20_infl", "y30_zcis" I ...
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Search file name within file

Someone put a lot of malicious code onto every single wordpress instance on my server. For the second time. (At least) Every js file has been modified. There is a pattern though, the code always looks ...
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find: list all directories except those with numbers in their names and their children

I am running the following to find all directories without a number in them (not including the original path): find /path/2/directory -type d -name '[!0-9]*' The problem is that it finds ...
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60 views

multi line awk regular expression [duplicate]

Consider text.txt with this content: blablabla &&&key word&&& I want all these text and numbers 123 and chars !"£$%& as output &&&key word&&& ...
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46 views

Extract Strings from Web Log file

Given a file containing web access logs for a YouTube video, every line is a hit and is in the format. 62.172.72.131 - - [02/Jan/2003:02:06:41 -0700] "GET /random/html/riaa_hacked/ HTTP/1.0" 200 ...
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How can I use part of match in Regex to generate filename of action?

I am using CentOS6.5 that include rsyslogd v5.8.10 There are 20 process program in my server.I want to receive logs use rsyslogd and hope to store in different log file according identity of process ...
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regular expression's $ character

I know when I use $, it means characters before $ must be shown at the end of the string. But, I don't know difference between the tests given below, when the variable a is integer: [[ a =~ -?[0-9]+...
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Egrep back referencing not working

I have trying top back reference the first captured group in the below command: $ ls -lR | egrep 'd(rw(x|s)|rw-|r-(x|s)|-w(x|s)|r--|-w-|--(x|s))(rw(x|s)|rw-|r-(x|s)|-w(x|s)|r--|-w-|--(x|s))---' drwxr-...
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sed backreference: get each line and append it to end of line

I have a file with following content: $ cat -n w 1 Smith John 12345 jsmith 2 Jones Robert 23456 rjones 3 Green Ralph 34567 rgreen 4 Brown Fred 45678 ...
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pattern regex for apache rewrite

I have a bunch of URLs counting to thousands i need to redirect and there are thre main patterns in URL first pattern There is a dash - starting the title url and want to remove that dash e..g www....
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50 views

Grep: Why escape modifiers?

By modifiers I mean the following: -\{m\} exactly m repetitions of previous character - \{m,\} at least m repetitions of previous character - \{m,n\} any number of repetitions of prev char between m ...
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Bash - Regex to match tuples of numbers

I want to check if a string that has been written to a variable in bash via the read command is a tuple of two numbers. To my knowledge, this should be possible with if [[ "$input" =~ "$regex" ]]; ...
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Why does perl regex find pattern \\label\{.*?\} but not \\ref.*?\} or \\autoref\{.*?\} in TeX Files?

I am using perl to parse many multilingual text files. I need to change the text between two patterns: Desired Changes For example, the English original version looks like this: \label{whatever} \...
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25 views

Piping difference of grep -c's with different regex to bc

I need to find the number of words in a file (1 word per line) that do not contain some set of letters. To do this I want to take the difference of grep -c '.' <file> and grep -c '<...