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

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bash regex: asterisk metacharacter kills redundant newline characters

To test the basic functioning of the asterisk metacharacter in search operations using grep, I used a file (regex.txt) with the following contents: $ cat regex.txt 1 11 111 1111 11111 $ There ...
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Java comments regex: egrep “(/\*\* | /* | \*/ | \*\*/)” text.txt

I'm trying to extract lines starting or ending a Java comment: What I have is: egrep "(/** | /* | */ | **/)" text.txt I noticed that this works for all lines (such as /* comment */) except ...
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53 views

sed - simple regular expression replacement not replacing

I'm trying to use sed to remove any subdomain prefix from a list of hostnames, but it's not replacing anything when I use a regular expression. Here's the simplified example that's not working: echo ...
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63 views

Using a shell variable with grep [closed]

I have a list of tokens in a text file and want to use grep to get the lines from a second text file that contain those tokens, but seem to be having trouble accessing the shell variable with grep: ...
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37 views

Remove word after match

Consider the following line of text (taken from a MySQL insert): "description" varchar(255) COLLATE utf8_unicode_ci NOT NULL DEFAULT '', I want to return "description" varchar(255) NOT NULL ...
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Awk & regular expression to process pgn chess games file

Below an extract of the sample.pgn file [Event "rated blitz match"] [Site "Internet Chess Server"] [Date "2015.08.20"] [Round "?"] [White "Villain"] [Black "Hero"] [Result "0-1"] [WhiteElo "1643"] ...
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Remove words (letters followed by space) from a specific column

I have a file and the format is as follows: cat dog AHF123432 | 123432 | dhfshfjdh lion AFG23412 |23412 | dfshjhfjdhj I need to remove those words from first column which contains only alphabets ...
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How to express “There is a specified symbol in the following unknown numbers of characters” in regex(vim)?

I have many python code examples in my markdown files, which should be prepended with >>> symbols. So I write a vim function to do this job: function AddShellPrompt() range let lnum = ...
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35 views

Locate --regex with negative lookahead

Problem I tried to implement a negative lookahead when searching a file with locate like this: locate --regex "apple(?!t)" However I'm getting the following error, because there seems to be some ...
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208 views

UltraEdit - regular expressions replacement

I was trying many different combinations without success, at this point I would be really grateful for your help. I need to replace this end of the line multiple times (around 300) and it would be ...
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118 views

How to write a regex to look for strings with fixed length with at least one occurrence of a character

I've been doing some reading on regular expressions and thought I had everything covered, until recently. I've had to filter out all strings of length 5 which end with the letter t and contain at ...
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93 views

sed exception handling of escaped characters

I want to delete anything that follows a % to the end of the line. Using cat /tmp/foo.txt | sed 's/%.*$//' works great with one exception: I want to ignore any escaped percent signs \%. So with ...
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105 views

Find only in directories n levels deep

I use this command to find and run all istances of wp-cron.php I have for each site I have: find /var/www/ -name 'wp-cron.php' -exec php -q "{}" \; Since my websites tree is: ...
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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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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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104 views

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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112 views

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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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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222 views

Retrieving words before certain characters without having to use Perl

I have where clauses for SQL queries in text form, and I'd like to extract the column names from them. The clauses can contain conditions like col_1 = 'Spruce' and col_2 in ('Argentina', 'Cameroon'). ...
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36 views

some POSIX Bracket Expressions not working

For example when I'm trying to find and replace something using g/[:digit:]/s/1/2/g Vim showing error: Pattern not found: [:digit:], while the string contains digits. Following POSIX Bracket ...
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105 views

How can I use regex to extract the text following two conditions into a variable?

I'd like to extract a setting for a given host in the ssh_config file and put it into a variable. Host mysite HostName 123.1.1.1 User myuser Port 13245 GSSAPIAuthentication no ...
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150 views

How to nest global matches with sed?

If I do: sed 's/match/replace/g' I know that sed will substitute replace for every occurrence of match on a line. But what if...? echo "match <please dont match this?>" | sed ...
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Remove patterns from string using bash

I'm trying to remove some patterns from a file input string (parsing file line by line). Here is a sample string: 1: (10/17 12:49:31.175) - CONSTANT ID1 - CONSTANT ID2: RAW DATA OUT > ...
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Regex for contains at least one instance of STRINGA and no instances of STRINGB

What regex will match: contains at least one instance of "1221", and no instances of "7474" i.e. matches "7777 1221 4543" but does not match "7777 1221 7474 4543" I suspect I have to use negative ...
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Why does the same sed regex (after grep) fail when run in a bash script vs bash command line?

Here's the script. It is successful when I run it from the BASH prompt, but not in the script. Any ideas? When I say "fails," I mean the sed regex doesn't match anything, so there is no replaced ...
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How to get the JSON STRING from the given string

I have a string given below. I just need to get the first accountHeader (bolded) JSON string, I tried everything.. It didn't work. Can you help me to get the data? <START ...
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Where can I find documentation on shell script syntax for using a regex within a variable construct?

I'm debugging a shell script (which I didn't write) that contains this loop: read line < "$pid_file" for p in $line ; do [ -z "${p//[0-9]/}" -a -d "/proc/$p" ] && pid="$pid $p" done ...
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Parsing csv with sed and perl one-liner?

I have a web server which stores configurations to PostgreSQL, and I plan to retrieve information from a certain table and then later parse it into csv format. PAYLOAD <?xml version="1.0" ...
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126 views

Help understanding an egrep expression

I stumbled across the following egrep expression: egrep '^([^aieou]*[aieou]){5,7}[^aieou]*$' /usr/share/dict/words on this page: http://matt.might.net/articles/sculpting-text The expression is ...
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579 views

Brace expression does not work in find regex

I have two folders, CA01 and CA02 under current folder, foo: foo -+ | +-CA01 | +-CA02 When I type find . -regex ".*CA[0-9]+" -exec echo {} + Or find . -regex ...
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Tell a regex expression to skip the beginning of a line before matching

If I had a string like 45mb ./aaaa/bbbb/cccc/dddd and I use a regex like [^\/]*\/ it will match 45mb ./aaaa/bbbb/cccc/ I only want it to match ./aaaa/bbbb/cccc/ but I can't figure out how to do ...
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Matching hexadecimals with gawk

I have a binary file with the following content (printed in hexadecimal): $ xxd -p virus.com 5669727573b440bb0100b90500ba0000cd21 I can match the first 5 letters (which are the alphanumeric string ...
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linux + match IP ADDRESS with 3 octets or with 4 octets

how to match IP address with 4 octets or with 3 octets in one command? target - match xxx.xxx.xxx or xxx.xxx.xxx.xxx ( syntax should fit for Linux and Solaris ) how to merge the following commands ...
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Recursively edit files based on parent directory's name

I'm facing an issue I'm not quite sure how to overcome. I have a large directory with hundreds of folders, all following the naming scheme "a_b_x", with x being a random word. In every one of these ...
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Regular expression how to get value in shell script?

I have to write a shell script to get value from a string, something like: string="abcdef" pathName How can I use grep command with the use of regular expression to get "pathName"?
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awk extended pattern matching (embedding pattern matching in actions for already matched strings) [closed]

I want handle strings of the form: PREFIX_TYPE_N,DATA So, does the *awk (gawk, mawk, nawk) support including pattern matching in the action for already matched string? Something like this (of ...
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Multiply certain numbers in a text -file by certain constant

I want an alternative solution to this jQuery hack, tasting a bit reinventing the wheel -- look I am sure I could do this with some one-liner using basic *ix tools. Look much easier and ...
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225 views

What special characters does grep parse by default? [duplicate]

Possible Duplicate: In a regular expression, which characters need escaping? I know there is the -E flag which treats the "search term" as a regular expression. However, it seems that even ...
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343 views

Easy Regex on Apache Logs

I'm struggling to create a regex for Apache logs. It's for ignoreregex on Fail2ban. I'd really like to be able to put something like /house to catch all files in that directory or ...
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Regex on Postfix using Centos

I have a Centos server running only postfix. I want to filter out mails containing word gratis or grátis or grétis or grâtis. The second letter is the problem. So I used this rejex: ...
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Why is vi (but not cat) showing ^[[31m[^[[m^[[31m" after I use sed and output to a file I then edit? [closed]

When I use cat Variables/user-extensions.js | sed -e 's/css/XXX/' on an input file of the form storedVars["css_body"] = "css=body"; storedVars["css_main"] = "css=main"; I see output such as ...
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what is the correct regexp for mysql filter in fail2ban?

I use the default filter file /etc/fail2ban/filter.d/mysqld-auth.conf for fail2ban service. But there are some errors in file /var/log/fail2ban.log as: Found a match for '150815 10:42:54 [Warning] ...
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LFTP exclude file extensions

I am trying to mirror directories with lftp but I don't want to download filetypes that are notoriously large like .mp4 and .swf. But I am having trouble with the regex - and seeming like the ...
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regex usage in exim filtering

I'm trying to create an exim filter to block spam messages containing " 85% OFF" in the subject line. That's a blank space, then any two digits, then the percent sign, a blank space and the ...
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Interpreting regex wildcards with grep [duplicate]

This is a really simple question, but even after reading about wildcards/regex, I can't seem to grasp entirely what the differences between these commands are: grep . test.txt this one will look ...
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How to do operation on individual matches in a full line

I have a Verilog line like this: if (i2_0&!(i2_1)) (posedge i0_0 => (o:1'b1))=(0, 0); How can I convert it to a line like: if (i2_0 == 1'b1 & i2_1 == 1'b0) (posedge i0_0 => (o:1'b1))=(0, 0); ...
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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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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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136 views

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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Take the unknown contents of variable as literal in sed [duplicate]

I have two files: a.patterns contains patterns in a one per line way "`" "^" "<" "<(" "<)" "<[" "=" ">" "_;|^+*+?@" and b.data contains comma separated values. 1,1,0,"*",1 ...