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

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Vim: Substitute based on another match in the line

I have rather large files in which I need to substitute NX for N1 but only if the line already contains NX as a pattern. So far I do it manually by first searching for occurrences of NX with: /NX ...
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383 views

How to perform grep onto the output of ldd properly ?

# ldd /usr/bin/ffmpeg linux-vdso.so.1 => (0x00007ffffc1fe000) libavfilter.so.0 => not found libpostproc.so.51 => not found libswscale.so.0 => not found ...
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How to replace a word with new line

I have a text file with following data and each row ends with |END|. T|somthing|something|END|T|something2|something2|END| I am tryig to replace |END| with \n new line with sed. sed ...
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How to grep the n-th substring between given delimiters?

Let's say we have a string and its delimiter is ?: Leslie Cheung April 1 ? Elvis August 16 ? Leonard Nimoy February 27 I know how to grep the first substring between delimiters: echo $above_string ...
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1answer
73 views

Pattern matching and removal of that pattern using sed

I have 2 files with the following names: File 1: RvA_X-IRB-bil-CA101-0+010000-20150327212332-055582-P File 2: RvA_X-IRB-bil-CA101-1+020000-20150327212332-055582-P I am using this command to match ...
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grep log lines of a specific id request

So, I have the following log sample: 2015-03-30 10:19:44,200 DEBUG [Default : 1] [Application:ABC BIW: IDA:6d87de8e-1276-4496-b49d-dd4cd375cbe4 Info:P23 Code:ABCD] A log message 1 2015-03-30 ...
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Parsing C Style Multiline Comment

I want to filter non-commented javascript with sed and output the line number Here is the example: /*! * jQuery UI 1.8.17 * * Copyright 2011, AUTHORS.txt (http://jqueryui.com/about) * Dual ...
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AWK print regex pattern

I am trying to print a regex pattern for the following piece of mail log. In particular I am trying to get the ID between the square brackets (see the second line for reference). Mar 29 03:48:13 ...
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532 views

regular expression to extract information in shell script

I would to grep certain parts of some shell command output in the shell script: $ uname -r >> 3.14.37-1-lts Where I just need the 3.14.37. And also for the shell script variable VERSION that ...
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Is it possible to get static backreference with grep?

I try to match a a group twice in multiline. grep -Pz 'Source: (?<group>.*/).*\n.*\n.*\n.*\k<group>|$' it work except one major problem - it doesn't, \k<group> search for .*/ and ...
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Shell test to find a pattern in a string

I just wanted to ask whether there is any command which would work on common shells (bash, dash, kornshell)? It is supposed to check if the line variable contains any part of the path. if [[ $line =~ ...
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49 views

Bourne shell: ignoring certain kinds of stdin

I have a program that is currently working, but I need to modify it to ignore some stdin that is not fitting for its correct function. Right now, to run the program: printf "1\n3\n5\n" | sh prog The ...
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127 views

Using regular expressions to search a word list. Finding 2 letter words instead of 3. Why?

I am studying regular expressions and I am stumped. Here is my process so far.... I downloaded this file. wget http://www.mieliestronk.com/corncob_lowercase.txt mv corncob_lowercase.txt words.txt ...
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How to search mail logs effectively with `RegEx`

I was looking for some advice and examples on searching mail log effectively Suppose situation is like this -------- Forwarded Message -------- Subject: Fwd: Re: Notice of Allowance Date: Fri, 13 ...
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Regular expression that ignores certain characters

I need to find a regular expression, that ignores certain characters for usage in the bib2bib tool. For example: I need to find any occurence of the word "muller". But also a string like ''Hello, ...
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How to use variables in substitution with vim regular expressions

I have a big file that contains among others serveral lines of the following form: USet07-1 USet07-2 USet08-1 USet08-2 . . . USet22-2 . . . I want to remove the hyphen/dash - from these strings in ...
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Pages don't get blocked with Squid over HTTPS

I have set up Squid to block pages on my own system (i.e not on a network), and I'm trying to get SSL to work with page blocking. To this end, I've set up ssl-bump and installed the certificate to my ...
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1answer
127 views

Problem with sed substition in multi-word regex

Take this simple example: echo "20150310 21:12:01.846338::: <?xml version="1.0"?><Haystack><Event " \ | sed 's/^\(.\{24\}\)::: \(<?xml.*><Haystack\|Foo\)>\(.*\)/\2 ...
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effect of [0-9]* in a regular expression

What is the function of [0-9]* in the following statement, which will write all lines that start with an even number, followed by a space, to the file even: sed -n 's/^[0-9]*[02468] /&/w even' ...
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Emacs: query-replace prepend text to the found string

The scenario is that I am trying to append a new class to all the style declrations in my css file. So .oldclass{ float : left; } should change to .newclass .oldclass{ float : left; } The ...
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Regular expression for excluding data within a certain range

I want to remove all the IP addresses which are of the format 10.20.30.* and whose last 3 digits fall in the range 0 to 200 and move all the remaining IPs to a new file. I've put the IP list to be ...
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SED: print entire paragraph for specific pattern while loop

I find partial answer about my problem on this question but i still have trouble. I need to use a variable as a pattern for the sed command in a loop sed -e '/./{H;$!d;}' -e 'x;/'$var'/!d;' The ...
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To remove \n but not \n\n

Data 23. Lorem A) he B) ha C) hu c 2. Ipsun yes right to write something here? A) Ok B) No C) yes b 292. Ipsun A) Apex B) hello b 289. He A) hu B) Ha C) He The right answer is: 1) Ab 2) Abc 3) ...
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Searching file for string surrounded by two other known string?

Question title may be kinda vague, but heres what im attempting to do. I have a html file locally on my server which is changing fairly regularly. It has multiple occurrences of: <p>Jumble of ...
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how to modify matches to a regular expression with sed or another tool?

I need to manipulate text that's in a file. I need to append a right parenthesis – ) – after every number that's preceded by a comma – , – e.g., ,4   ➜ ,4) ,15 ➜ ,15) I am struggling to find the ...
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How to search parenthesis by ack

I want to search for a parentheis ( using ack, but neither using ( nor \( worked. The first one ("(") is recognized as a multiple line command. The second one ("\(") is treated as an invalid regular ...
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What is SELinux's regex type?

I'm trying to locate all files on my system matching an SELinux file context (fcontext). These contexts are specified using some regex, and I'd like to use find -regex ... to the same effect. However, ...
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43 views

Printing out range of a pattern with awk

Im trying to print out a section of a txt file using awk. Basically I want to print out the paragraph in the a txt file that begins with certain words all up to a blank line.Here's what I have so far: ...
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Grep all string which do not starts with number(s)

I'm looking for grep to show all characters which do not starts with numbers. I have done something like this: grep -v '^[1-2]*[a-zA-Z]?' -o but it do not work. Do you have any idea for some reg ...
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SED and regex expressions… addr1 and addr2

How can I use sed to match 'addr1' and reuse it again in 'addr2' field? #Ex.: echo "12a34" | sed 's/a/#bcd/g' # 12abcd34 #\# = match addr1
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What is the meaning of (^| )ABC( |$) as an extended REGEX ?

I came here across the command grep -E '(^| )ABC( |$)' file1 I am confused how to interpret the regular expression therein, because I know the ^ and $ character as beginning and end signifier, but in ...
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1answer
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How to grep exact word with only space as word separator

For Example: I have file like following: AA ABC-AA-AA AAA ABC-AA ABC.AA ABC AA ABC.A AA If I use grep -w "ABC" file1, I am getting all the lines. But I should only get 3rd line: ABC.AA ABC It is ...
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How to change a single line in multiple files [duplicate]

I have ~750 .php files in the same directory that contain the line include("path/to/file.php"); I would like to change this line in every file to require_once("path/to/file.php"); What would be ...
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Why is logcheck reporting successful Horde logins?

I'm running Ubuntu 14.04 LTS server and use logcheck to report log messages. I have the logcheck-database installed which contains a horde3 ignore file for the server: ^\w{3} [ :0-9]{11} ...
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How to delete html tags from a file using sed ?

I have a file that is mixed with both normal text I need and html-tags. I know that with REGEX it is possible to recognize html tags and with sed one can swap those for an empty string, but I do not ...
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637 views

How to find with grep lines that end in a certain string?

I know that to find a REGEX that ends in a certain string I have to write "string$". Although I tried the following variations of grep : cat foo | grep "string$", cat foo | egrep "string$", grep -E ...
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What regular expression in grep searches for strings of three same letters in a row?

I have a text file and I am using the grep command with a regular expression to get only the lines which contain three same successive letters, e.g.: aaa bbb ccc ddd What regular expression do I ...
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How do I use the regular pattern operator {m,n} in grep?

I have a text file, from which I need to select only those lines, which include the string "tt". So I tried this on the command line: grep "t{2}" textfile Allthough I know the textfile contains ...
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How can I find and replace only if a match forms a whole word?

My script is: n="y" while [ "{n}" = "y" ] if [ $n == "n" ]; then break; fi echo "n is $n" do read -p "Enter the word to find = " word read -p "Enter word to replace = " replace ...
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Regex for matchng anything between parenthesis

I have the following regex so far: printf "this is (test.com)\n" | grep -Po '(?<=\().*(?=\))' The above regex will print the desired output, which is test.com As far as I am adding new ...
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1answer
119 views

What is the Difference between Regex `[]*` and `[]+`?

I started learning regex recently. I know that * modifier means match 0 or more times while + modifier means match 1 or more times. However when you use these modifiers with square brackets, how ...
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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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sed regex not working for hidden characters

I have a list that has for some reason got some non alphanumeric characters appended to the end. I would have thought it would be a simple case of running : sed 's/[^A-Za-z0-9]$//' To replace ...
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Using sed to remove digit separation commas enclosed in quotes and quotes itself from CSV? [duplicate]

How can I can use sed to remove from before-last column the group digit char comma and quotes itself? Please note that in the sample below the target column is not contained in double quotes. ...
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Substitute all occurrences of pattern with first matched group

I have to go from this: text match$something_here and match$xxx blablabla text match$something_else_here and match$xxx blablabla ... to this: text match$something_here and match$something_here ...
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Coordinates X237595Y81600 to X2375Y8160

I have create a gerber file and it has lines inside which look like this: X90095Y15350 X100095Y15350 X110095Y15350 X120095Y15350 X120095Y25350 X110095Y25350 X100095Y25350 X90095Y25350 X80095Y25350 ...
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Why awk understand FS=“*” but not for FS=“-*-”?

I got a test file, its content is: a -*- b I used awk 'BEGIN {FS="*"} {print $2}' test, it prints out - b Correct! But when I use awk 'BEGIN {FS="-*-"} {print $2}' test, I got: * I know that ...
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What types of regex DO support (e.g.) negative lookbehind?

Bash on GNU: I am using a collection of find commands, most of which employ -regex to do their matching. Each time I try a different feature in my regex I have to cycle through the values for ...
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435 views

Sed with angle brackets

This works sed 's/[[:space:]]*<default>false/XXX/' Why does prepending a > make it fail sed 's/>[[:space:]]*<default>false/XXX/' escaping the > does not help either. In ...
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261 views

sed to replace a word from a file with the contents of another file? [duplicate]

I have two files file1 & file2. Contents of file1: Text1 Text2 Text3 Contents of file2: Sample1 Sample2 Sample3 I would like to replace the word Text1 from file1 with the contents of ...