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

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Finding special characters in name

How do I find files that have ~ * and other special characters in the name? e.g. find . -name "*\*" should match "any characters" and then *, but it matches nothing; how can I get the command to ...
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Matching number using grep [on hold]

I have this text: yuiopao:##yuiopao:14975:Alex Vart student:/home/stud/yuiopao:/bin/bash polkovar:##polkovar:5004:John Adi student:/home/stud/polkovar:/bin/bash gfgfdgd:##gfgfdgd:11000:Alan ...
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31 views

Regex in find - OS X

I cannot figure out what's wrong with my regex, it seems to be working with grep but now with find. I'm trying to find all the files which follow the common expression in TV shows e.g. S02E21. find ...
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2answers
33 views

How to get numbers of specified (range of) length from string with grep?

Here I have a bash "one-liner": cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 16 | head -n 16 | grep '[0-9]', which generate 16 lines of 16 character alphanumeric strings. Example of output: ...
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1answer
72 views

Pattern matching [duplicate]

I am trying to follow Bash Cookbook to learn about Bash Scripting. I am on example 6.8 Testing with Regular Expression. I have the following script: #!/usr/bin/env bash # cookbook filename: ...
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1answer
48 views

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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1answer
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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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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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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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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250 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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Does grep “-n” option change the number of the lines depending on the regex search? [closed]

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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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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3answers
261 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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92 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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3answers
43 views

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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3answers
50 views

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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2answers
31 views

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: ...
2
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1answer
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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2answers
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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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
52 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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3answers
78 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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69 views

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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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
31 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
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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 ...
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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 ...
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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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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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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] ...
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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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1answer
47 views

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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1answer
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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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3answers
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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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1answer
34 views

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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1answer
31 views

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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169 views

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 ...
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 ...
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223 views

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 ...