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

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egrep doesn't work as expected on SunOS system

Here is what I want to achieve on SunOS: Only pattern like [text_text=text], [text=text], [text] or text are valid patterns, where by text I mean anything in 0-9,a-z,A-Z, space, newline, tab, enter. ...
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1k views

Why does `grep fil*` fail?

I found echo file|grep fil* fails, but echo abcd|grep abc* succeeds. I don't understand it, can someone explain? Thanks
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249 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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sed regular expression behaving differently than in vim and perl?

Here's a sample 'test.txt' abcdX1yad45das abcdX2fad45das abcdX3had45das abcdX4wad45das abcdX5mad45das sample desired output: X1yad X2fad X3had X4wad X5mad I could get it working in vim with: :% ...
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How can I extract/parse a complete URL from a semi random string?

I'd like to have bash parse/extract a full URL (and only the url) from a random short string. Examples: bob, the address is http://www.google.com or https://foo.com/category/example.html is up ...
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only regular expressions : i want the lastnames that start with A or R [duplicate]

name ,lastname,phonenumber Hace, Apoio, 703-2101 Yoliot, Apostolos, 4222-1124 Jenny,Thano,105-4122 Aeriom,Koun, 510-4122 Dekon, Atolo, 502-2522 Feow, R,685-3431 I did this but doesnt worked and ...
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89 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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What is the meaning of :- in unix? [duplicate]

Trying to understand the existing script where they have assigned ${3:-} to variable. Script : partition_parameter=${3:-} if [ -z $partition_parameter ]; then readonly drop_partition=false ...
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1answer
26 views

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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Use of \$ at end of variable name passed to grep

I was going through one of the shell scripts and found a line: ls $dir | grep -c "$NAME.${var}\$" I understand that $ would expand the variables NAME and var, but is it required to put \$ at the ...
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Replacing regex “$” does nothing for some lines? [closed]

I have a text document, I want to add < to the end of every line, I thought I could use this: sed 's/$/</g' But for some lines, nothing happens. I thought it was because of special ...
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Can grep output only specified groupings that match?

Say I have a file: # file: 'test.txt' foobar bash 1 bash foobar happy foobar I only want to know what words appear after "foobar", so I can use this regex: "foobar \(\w\+\)" The parenthesis ...
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58 views

Does grep “-n” option change the number of the lines depending on the regex search? [on hold]

I've been working with grep on cygwin and I need the line number of a pattern; so if I write: grep -P -a -nh -i -- "ELEVATION|(\d+(\s+)?(FEET|FEETS|FT|METER|METERS))" * one of the outputs is this: ...
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21 views

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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Regexp in .ssh/config

At work, I often have to log into hosts which follow a common naming scheme, e.g. qc01 - qc12, hc01 - hc10, and so on. All of these need to get the same config values in my laptop's .ssh/config. Of ...
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2answers
30 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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1answer
782 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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How to search and replace multiple needles by one word via one expression?

Assume you have a text file: foo fnord bar bizz foo poit And now I would want to replace both "foo" and "bar" into "narf". I know I could use: sed -e 's/foo/narf/g' -e 's/bar/narf/g' fileName ...
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3answers
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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 ...
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258 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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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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35 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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46 views

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
631 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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1answer
49 views

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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74 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 ...
13
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1answer
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Replace using VIM, reuse part of the search pattern

I am working with VIm and trying to set up a search and replace command to do some replacements where I can re-use the regular expression that is part of my search string. A simple example would be a ...
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2answers
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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 ...
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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 ...
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3answers
30 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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1answer
32 views

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 ...
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Curl and grep html text

Is there a way to grep html text from a curl request and output grab the value that is between two html tags? More specifically the input value of a form?
24
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3answers
31k views

How to run grep with multiple AND patterns?

I would like to get the multi pattern match with implicit AND between patterns, i.e. equivalent to running several greps in a sequence: grep pattern1 | grep pattern2 | ... So how to convert it to ...
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2answers
24 views

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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scp a file to multiple folders

I wanted to scp file.txt to remote box my-remote-vm-1 In my-remote-vm-1 there are two folders conf-1-ver-2,conf-2-ver-2. The integer part in the folder name can go from [0-9]. What would be the best ...
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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 ...
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1answer
28 views

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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2answers
34 views

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 ...
4
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0answers
42 views

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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1answer
30 views

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] ...
0
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2answers
53 views

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: ...
3
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1answer
87 views

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 ...