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

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Remove string from a particular field using awk/sed

I have a file (>80,000 lines) that looks likes this: chr1 GTF2GFF chromosome 1 249213345 . . . ID=chr1;Name=chr1 chr1 GTF2GFF gene 11874 14408 . + . ...
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with sed, how can I replace word within a matching line?

I am trying to write a sed expression to detect lines similer to this: s0:12345:respawn:/sbin/agetty -8 -s 115200 ttyS0 linux and replace the "ttys0" with "something_else" I do not want to detect ...
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375 views

match files based on an md5 using find

I have a bunch js and css files in a directory. Some of them have been given a name based on an md5() of their content (looks like f10521a21bb013cb81e0909809818ad6.js). I'd like to match these files ...
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how to use regex in alias?

I want to create the alias for the command "ssh user@10.32.44.225" as 10.32.44.225 alias [0-9][0-9][0-9].[0-9][0-9][0-9].[0-9][0-9][0-9].[0-9][0-9][0-9]="ssh user@$0" I have created it, but it is ...
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VIM substitute occurrences of pattern after a particular word in a line

I have such lines in my text. text before pattern = garbage** text after pattern is pattern If in VIM I do %s/pattern/saturn/ it replaces all occurrences of pattern. But I only want to replace ...
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Emacs simple arithmetics in query replace

Is it possible to do the following in emacs: Query replace all numbers in a region by the number +n, for example if you have: 12 and 7 are nice numbers let n be 3, then it should transform to 15 ...
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escaping a single dot with double backslash - awk

"effective awk programming" book has an example on Field-Splitting. here is the example: If you want fields to be separated by a literal period followed by any single character, use ‘FS = ...
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Replace a substring of filenames in a directory

There exists a directory, which includes several levels of sub-directories. Under these directories, there are a set of files whose names include a common word, e.g, .cc. How can I replace the .cc ...
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substrings and regexps

I have a string contained in a variable, and I want to extract substrings based on position relative to another substring. My solution seems to work unless the string is sent to a function as an arg. ...
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214 views

Insert Lines after Multi-Line Regex Match

I've got an XML file I need to append to after a specific set of tags. Basically the file structure looks like this: <key>servers</key> <dict> ... Server Details ... </dict> ...
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substituting third occurrence of a pattern using sed

Here is a sed command. I want to substitute third occurrence of 00 to 11 echo "0000000000000000" | sed -e 's/00/11/3' The output is: 0000110000000000 But I thought output would be: ...
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Substituting the first occurrence of a pattern in a line, for all the lines in a file with sed

Is it possible to do it in one liner? I have an output like this: "First line" - Description " Second line" - Description "Third line" - Description " Fourth line" - Description This input ...
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How to find files with names having a long string after the first dot

My Samsung Galaxy S doesn't like files where the name contains a long string after the first dot. I guess some part of the software has a too short buffer for the file extension. How can I find all ...
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regexp which matches all tokens independent of order

I have a quick (and hopefully simple) question about regexps. I'm trying to think of a regexp which matches all of a set of tokens irrespective of order. So for example I have a file with the names ...
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syntax of ls --hide= and ls --ignore=

ls --hide and ls --ignore provides the possibility leave out files defined through regular expressions set after the --ignore= part. The latter makes sure that this option isn't turned off via -a, -A. ...
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greedy and lazy regular expressions (comprehension question)

I am teaching myself regular expressions, and I got stuck at »greedy« vs. »lazy« repeatings. What I found out so far is that »greedy« means that the RegExp ...
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find command with regex {1,2}

I have been trying to create a find command string that will find all files that end with a number 1-99 but exclude all others. e.g. I want to find myfile1 myfile99 but not myfile456 and not ...
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Find files in multiple folder names

I am trying to list all the files from dir1, dir2, dir3 and dir4 which might be anywhere in as a sub directory of my cwd using the find command. I tried the following with no success: find . -type f ...
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1answer
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Regex this question format into LaTeX

1. Lorem ipsun la la la? 1. Sopor 2. Stupor 3. Torpor 2. A patient has Lorem? 1. Sopor 2. Stupor 3. Somnolentia 4. La 5. Coma 3. Doesn't Response to strong external irritants is short. Tendon, ...
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1answer
828 views

Match word containing characters beyond a-zA-Z

To match a word one can use \v(\w+) From the vim help :h \w: \w word character: [0-9A-Za-z_] This works exactly as described in the manual. However, I want to match words that contain ...
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File manager which is able to filter using regular expressions

Is there any graphical file-manager which supports thumbnails for linux like thunar or nautilus, which allows me to filter a directory by a regular expression. For example typing /home/user/*tex ...
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Replace using vim - Replace a pattern […] by a string

I have a file containing lines in below e.g. format - [foo@host.com, bar@host.com], Payment processed - 23499, params = {'invoice':3243} I only want the account numbers i.e. 23499. It's a number. ...
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sed regex issue

I'm trying to replace a string in a file: $RELEASE = '1234'; The whitespace between RELEASE and the = symbol could be either spaces OR tabs. The quotes around the version number could be either ...
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rsync certain files, excluding the rest, ignoring .svn/ directory, recursively

I'm using rsync to copy some files from a share to another. Recursively, I need to: Delete files at destination that were removed from the origin Only sync php and js files Exclude every other file ...
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1answer
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Using Regex in vim movment

Is there any way to use regular expression for movement in vim. For example, I want to move my cursor to the first occurrence of the pattern abc. So can I do something analogous to fa but now a ...
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806 views

Is there a tool in linux that allows multi-line regex expressions?

I'm wanting to find the results of a multi-line regular expression in linux. I tried grep, but like most linux utilities it's line based. Is there something similar that allows me to search across ...
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501 views

Are there zero-width assertions in sed?

Is it possible to make lookahead or lookbehind zero-width assertions in sed? I want to emulate Perl's (?=) and family. My sed is not GNU sed version 4.0.
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Parsing XML from a shell script

I have a datafile like this: <Key name="com.ahsay.afc.cpf.UserGroup" content="" allowMultiple="Y"> <Value name="rsv-id" inheritParentAttribute="Y" type="string" data="1328200856753" ...
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Decreasing a number with sed

I extracted the metadata of a PDF in a .txt file using pdftk, and now I am trying to decrease the BookmarkPageNumber value for each bookmark by an integer. The .txt has these lines: BookmarkBegin ...
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Multiline regex blank line delimiters,

I have a program which prints out data in blocks. Each block is delimited by blank lines. I would like to discard most blocks and only keep those blocks that contain something that matches a regex. ...
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Why can't find -regex match a newline?

Why does this fail? touch "$(printf "a\nb")"; find . -regex './.\n.' I also tried these, none of which work: find . -regextype posix-extended -regex '.\n.' find . -regextype posix-awk -regex ...
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Regex not matching

why this does not match..? sed -e '/--Updated?[[:space:]]+Date/d' inputfile this..: --Updated Date: 2013-11-06 15:32:13 d? is because sometimes I have Update Date, and sometimes Updated Date. ...
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How to insert the content of a file into another file (if regexp) in shell/perl

File1 Contents: line1-file1 "1" line2-file1 "2" line3-file1 "3" line4-file1 "4" File2 Contents: line1-file2 "25" line2-file2 "24" Pointer-file2 "23" ...
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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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grep: regex only for match anything between parenthesis

How do I match word only between parenthesis Input : this is (test.com) Desire Output : test.com
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Using sed to find and replace complex string (preferrably with regex)

I have a file with the following contents: <username><![CDATA[name]]></username> <password><![CDATA[password]]></password> ...
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History of Bash globbing

Is there a historical reason why Bash "globbing" and regular expressions are not identical? For example, I believe that in Bash [1-2]* matches anything that starts with a 1 or a 2 followed by anything ...
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Delete XML node containing certain element

I want to remove all Placemarks from a KML file that contain the element <tessellate>. The following block should be wholly removed: <Placemark> ...
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How to “grep” a string of a returned result

How to grep the number 50.0 from the string temp=50.0'C In JavaScript I can use the expression /temp=(.*?)'C/ to get it. But I cant get it running in grep.
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Negative lookbehind/ahead assertions in Linux less pager (or vim)

I want to find all instances of "index" not followed by .php in a log using less. /index(?!\.php) does not work. Is this possible? What is the regex for less and vim (do they differ?). Is this not ...
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How to use restricted characters in egrep?

I'm trying to use a regex in egrep on Centos 5.10, based on the one I made from this question on SO. T12345 .{1,100}[\n\r].{1,100}2014.03.04 I can successfully match the regex to the content in my ...
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“grep: Unmatched [” error when using regex

I'm trying to find a pattern similar to this: tail -n 100000 gateway.log | grep -B10 -A10 'Nov 22 11:13:56 Received Packet from [10.50.98.68' Where "11:13:56" could be any time. This is what I ...
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changing pattern of a text file

A text file has contents something like chair table pen desk Now i want it to be changed and stored in a variable say var as below ('chair','chair'),('table','table'),('pen','pen'),('desk','desk') ...
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Awk: check for length of field

In awk. I am working on Solaris 10, so it's probably an old(er) version of awk. I came up with this rudimentary one-liner that works, at least for my particular input. awk -F\; '$3 ~ /[ ...
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Using regex inside if clause in bash

Look at this if block: #!/bin/bash str="m.m" if [[ "${str}" =~ "m\.m" ]]; then echo "matched" else echo "not matched" exit 1 fi exit 0 This should print "matched", but it doesn't. ...
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Applying a regex to stdin

In programing we often see the use of Regular Expressions. One of the most common forms is: newText = text.replace( /regex/, 'replacementString' ) If stdin is text and stdout is newText, what ...
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Regex match in CLI

Is there something like a logical for the cli? I want to achieve this mv -t newfolder *.(png|jpg) so that alls jpg and png files are moved into newfolder. I know it could be done with mv -t ...
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Extracting text from a text file in bash

I have a large text file that is all one line. In the text are several sections that looks like foo=12345 and I need to extract them all as separate lines, ignoring the rest of the file. For ...
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sed - how to (not) match unmatched brackets

How can I do my operation only on lines that close their brackets? For example I want to change ".is" lines and add a bracket but not for lines with unclosed brackets. so these are changed ...
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Replace all occurences of \ except \N

I have a file like this: 1,2,subjects,\mat\hs,unix\,\Nato,\N,123,\N I want to replace all occurences of \ with #, except for \N, such that the output looks like this: ...