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

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703 views

Awk regular expression syntax with number of repetition - different handling between gawk 3 and gawk 4

I am having trouble understanding or explaining why the following expression fails in gawk 3.1.x and yet works in gawk 4.1.x: (Minimum working example) echo ";#ADCDE#" | awk '/#.{5}#$/' -> produces ...
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195 views

Search for “not newline” in vim?

To search for A T\n in vim I can just do /A T\n What would be the equivalent for not newline at the end? /A T[^\n] did not work.
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1k views

Print some fields of /etc/passwd

I have a question concerning the usage of wild cards in Linux. Here I have some lines from a long list of lines in the /etc/passwd -file. root:x:0:0:root:/root:/bin/bash ...
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3answers
289 views

mv files to a different path which is constructed via a regex replacement

I have a directory full of files stored in subdirectories according to their filename, i.e.: 20d1/d325/52d1/20d1d32552d1a95249e62662fbdf924dd72c4027.jpg ...
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1answer
5k views

Confused about word boundary

I have been researching this a lot, but I am still not clear on it. What does word boundary mean? What does it do? So, for example, could someone explain this command to me please? egrep ...
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1k views

How to reverse-match a string in the Vim programming language?

I want to find the last index of any character in the [abc] set in the abcabc string but the search should start from the end of the string: " Returns the 0th index but I want the 5th. let ...
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2answers
637 views

How can I find matches with sed (or similar) for configuration parameters?

I'm pretty good at using php's preg_match (and similar) commands, and I'm also pretty good with regular expressions, but I don't do very well with sed. I have two shell scripts I'm working on and I'd ...
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1answer
4k views

sed special character replace not working in shell script

I want to write a script 'test.sh' that will take a user's input and replace all special characters with a '\' + the character. My script: #!/bin/bash echo 'input='"$1" arg=`echo "$1" | sed ...
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241 views

prepend digit to filenames which begin with digits (with zmv, please)

I have a directory with files named like 19.png, 20.jpeg, and README00.txt I want to rename these to 119.png, 120.jpeg, and README00.txt. I would like to do this with zmv as it works well in so many ...
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397 views

How to join vCards lines

vCard uses a special way to split long lines: At 75 characters, insert a DOS newline and a space. Joining therefore means to replace all occurrences of the sequence "CR, LF, space" with an empty ...
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Sort by regular expressions

I've got a set of POSIX regular expressions* ^BEGIN:VCARD\r$ ^VERSION[^A-Z] ^FN[^A-Z] ^N[^A-Z] ^NICKNAME[^A-Z] ^EMAIL[^A-Z] ^X-\([A-Z-]*\) ^TEL[^A-Z] ^ADR[^A-Z] ^ORG[^A-Z] ^TITLE[^A-Z] ^BDAY[^A-Z] ...
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743 views

Emacs: query-replace, regular expression, reuse of search result

How do I combine something like query-replace with a regular expression search-and-replace that in part reuses the search result? In my case, how to transform The programmers are "sort of" ...
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2answers
2k views

How do I transfer multiple files with a common suffix and prefix using an offset?

I have thousands of files whose names are of the form: sequence_1_0001.hmf sequence_1_0002.hmf sequence_1_0003.hmf ... sequence_1_0001.jpg sequence_1_0002.jpg sequence_1_0003.jpg ... ...
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143 views

Does find support OR in its regexes?

For example, I want to find all files in a directory that end in 'm' or 'sh'. The following works correctly: find . -regex '.*.m' -o -regex '.*.sh' But this fails: find . -regex '.*.(m|sh)' What ...
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How to treat a file as a single line with grep to apply a regexp search pattern?

I want to match everything that is between some lines with regexp but not this that match the start and the end. This sound to me as positive lookbehind and positive lookahead start text bla ...
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2answers
2k views

Arithmetic operations in regex

I am using gedit regex plugin (Python style regex). I would like to do some arithmetic operation on a backreference to a group. For example: PART 1 DATA MODELS Chapter 2 Entity-Relationship Model ...
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43 views

How do I match the beginning of a line in a manpage?

When I do man zshbuiltins I typically want to search for a command. Suppose I'm looking for info on the alias command. I get a chunk of text like: : [ arg ... ] This command does ...
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30 views

Why does this command remove more packages than I want it to?

When I run the following command: # apt-get purge unity-scopes-m* I expect it to delete the following packages: unity-scope-manpages unity-scope-musicstores unity-scope-musique Instead, it wants ...
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2answers
56 views

Can't get GNU grep 2.12 to handle LF character in regex expression

I've been at it for over an hour, but can't find why it's not working. I'm searching an HTML document for "\nSome text". Simple enough. But he following commands won't work: grep -Po ...
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3answers
54 views

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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94 views

How to search many files with regular expression and output matches to lines in a new file?

I have 1000's of source files and I would like to find all text that matches a regular expression and then output each match on its own line in a resulting text file. For instance; // a.cs string ...
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160 views

how to find files based on filename range?

I have some files with numeric names: 2341a.po, 4567211someword.po, 0012.po, etc. I would like to find a set of files based on the numeric range. such as [126 - 363]. Normally I use regular ...
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125 views

replace several comma out side one or more sets of curly braces and exception that in one or more sets of curly braces

In the text file I have multi records. Every record has multi column with comma separated, some column have one sets of curly brace and other have more than one curly brace. I need: If a comma is ...
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120 views

Find characters in the file

I need to find lines in the text file that have at least one x and at least two ys. I tried the following: grep -E "x.*y{2}" file.txt This method did not work. Is there another way to do it?
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Matching string with a fixed number of characters using grep

I am trying to find all 6 letter words using grep. I currently have this: grep "^.\{6\}$" myfile.txt However, I am finding that I am also getting results such as: étuis, étude. I suspect it has ...
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1answer
823 views

Removing non-printable characters using POSIX sed

Files created with roff and other "old-school" tools (for example man pages on many Unix systems) generate bold and underlined text in minimalistic terminals using tricks involving non-printable ASCII ...
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1answer
68 views

Context of the matching regular expression

I'm using egrep with the -o option in order to just get the matching part of the line, e.g. cat /usr/share/dict/words | egrep -o '(aa|ii)' Now I'd like to see some context of the match, i.e. a few ...
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A challenge for sed convert code from Mathematica to Matlab

I have the following output from Mathematica to C code: $ cat file.txt Complex(1.3, 2.7)*Power(kappa, 2.0) + Complex(0.3, 2.0)*Power(kappa,5.0)*log(alpha) The file is extremely long (many tens of ...
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1answer
249 views

csplit not obeying backslash r \r as carriage return

I have a file with \r\n line endings (CRLF carriage return line feed). This command works: $ csplit --silent --prefix=email-emailbad.txt- \ --digits=3 emailbad.txt '/^\.^M/'+1 '{*}' This ...
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Rename file in Mac OS Terminal using Regex

Hundreds of images need to be renamed with a terminal command using regex on MacOS 10.9 Mavericks. The files are named this way: 0045AW489R3T(IPCAM)_0_20131124101245_931.jpg ...
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153 views

Alternative regex for {}

I am trying to replace all of this line, but the numbers: looktype="123" so only the numbers show up. Is this possible in any easy way? {sub ("look type=\"[0-9]{0,3}", "TEST")} I am trying this ...
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483 views

vim regex to search for lines containing string1 AND string2

How in vim/vi can I search for all lines that contain string1 and string2, where either string can appear anywhere on the line separated by whitespace and possibly other words? I would also like to ...
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2answers
64 views

Trimming one part if equal to another part?

I use an e-mail quote attribution string like this: On dd mmm yyyy hh:mm +hhmm, from info@example.org (Example Dot Org): where info@example.org is the sender's e-mail address and Example Dot Org is ...
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How to tell grep to match special character at beginning of each word [duplicate]

I have certain questions regarding grep. Why does the following command match '<Hello'? $ grep -E "\<H" test Hello World <Hello H<ello What needs to be done to match '<Hello' only? ...
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1answer
672 views

Expand regex on multiple lines in Vim

I am working on removing comments from a C source file. Let's focus on multiline comments /* ... */ and ignore the inline ones (//) The following command seems to work with (solaris) sed: ...
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971 views

How to cut the output to only gather the filename and get-parameter?

I have multiple files with multiple links that are formatted like this: <a href="http://example.com/fnord.layername.html?parameter=FOO-_-BAR-_-FNORD" class="poit"> <img ... /> ...
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reference problem in using sed

I'm trying to use sed command to find/replace a pattern in file. It gives: sed: -e expression #1, char 27: invalid reference \1 on `s' command's RHS My command is: sed ...
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3answers
809 views

regexp in ksh for extensions tgz, tar.tgz

I'm trying to get a regexp (in ksh) to identify files with only the following extensions: tgz, tar.gz, TGZ and TAR.GZ. I tried several but can't get them to work. I'm using this regexp to select only ...
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1answer
46 views

How to use regex inside exec with find?

Is it possible to use regular expressions based on the result (file name) inside the exec argument with find? I want to be able to "exec" based on parts of the argument, like: find . -name pattern ...
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1answer
74 views

Match a number range with grep

I need to find all processes that have in their names a number between 100 and 200 inclusive. I tried ps -ef | grep xclock -bw '[1-2][0-9][0-9]' but that includes 299. How to suppress it and ...
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1answer
24 views

Seeing all regex matches in a file in Bash

I'm in bash and I have a file, I want to find all matches of a regex in it and have them printed. How do I do that? Followup: Assume I want to print only unique matches, i.e. if a match appears ...
2
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1answer
43 views

grep with regular expression

I want to match all the lines that are of the below pattern in a file using grep. Abc::xyz() [18-Feb-15 12:09:16] I came up with below regex with grep , but it is not returning match. Please help ...
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52 views

Match from current line until a line that doesn't match a pattern

I really tried searching but could not find anything (it's hard to know what exactly to search for). I know how to do this with sed: print from current line until the line that matches SOMETHING: ...
2
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1answer
186 views

To write this Pseudocode with Regex

I am doing a Makefile which I run regularly by Crontab every day at 0230 crontab -e; 30 2 * * * /bin/thePseudocode Python-like Pseudocode directories = ["Cardiology", "Rheumatology", "Surgery"] ...
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3answers
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bash: regular expressions in if expression

In my script on my ubuntu machine I declare a string like this: DEBUG_PACKAGE_LIST=$(apt-cache search dbg | awk '{ print $1 }' | grep -e "-dbg") For you to help you understand my problem here is ...
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1answer
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How to match a particular form of optional sequence from a manual synopsis, including variations?

In this Q&A there is a reference to the manpages synopses being based "loosely" on the Extended Backus–Naur Form of metasyntax notation. It's interesting and serves as background. That being said, ...
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2answers
161 views

procmail recipe with a regex doesn't work

In my ~/.procmailrc I have the following lines: :0 \* ^Subject:.*(O|o)pen( \|)(S|s)(onic|urge) $MAILDIR/OpenSurge/ As you see, I would like to put any mail containing “Open Surge” (or any variant ...
2
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1answer
381 views

Using regular experision in “rpl” command

I need to replace text in lots of files. I'm using rpl for this purpose, but I can't find any way to make it use regular expressions. Can rpl use "regex"? how? Edit: I'm using rpl 1.5.2 from Ubuntu ...
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697 views

rsyslog: make %syslogtag% equal length

I have rsyslog configured to log in the following format: $template long-iso,"%$NOW% %timereported:8:15% %syslogtag% %msg%\n" which produces logs like this one: 2013-12-14 15:59:39 ...
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2k views

Using BASH versus ASH on Synology

The majority of my photo files have the following naming convention / format IMG_20131204_120000.JPG, showing date and time the photo was taken (iPhone/Apple naming convention). However, not all my ...