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

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7
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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 ...
1
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3answers
150 views

To bold one line with Perl regex

I have 1. Lorem He he he % not sure spelling 2. Lorem ipsun I want to have \textbf{1. Lorem} He he he % not sure spelling \textbf{2. Lorem} ipsun My pseudocode attempt perl -000pe ...
2
votes
3answers
142 views

Apply item replacement inside enumerate in Perl regex?

Data 7. Masi is the same as \begin{enumerate} A B ABC ha lorem \end{enumerate} 1. ABC is \begin{enumerate} P B Lorem maam \end{enumerate} which I want to be 7. Masi is the same as ...
2
votes
3answers
820 views

Find a pattern with no repeated numbers in egrep

I need help finding a regular expression to match all digit sequences which has no repeated digit. Example: 198345 -> matched. 198315 -> not matched (1 repeated twice ) How can I achieve this in ...
2
votes
1answer
272 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 ...
0
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2answers
513 views

How to match date in Perl — assuming UNIX regex is the same as Perl's

I want to match dates of the form Monday May 26 My attempt to do this is the following: /(.*day Jan.*|Feb.*|Mar.*|Apr.*|May|Jun.*|Jul.*|Aug.*|Sep.*|Oct.*|Nov.*|Dec.* [1-31])/ The regex form in ...
3
votes
3answers
659 views

How can I get the first column of a 300GB txt file?

let me first explain my problem in detail. It's actually pretty simple. I have a huge .txt file, 300GB to be more preciese, and I would like to put all the distinct strings from the first column, that ...
1
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1answer
1k views

Interpret an interpolated variable as a literal string in Perl regex

I am using perl to colorize a matched string MATCH=aaa printf "aaa\n/dev/aaa\nccc\n" | perl -pe "s/($MATCH)/\e[1;31m\1\e[0m/g" This works well until I try to match a string containing special ...
3
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6answers
5k views

Regex that would grep numbers after specific string

So I have a line: ID: 54376 Can you help me make a regex that would only return numbers without "ID:"? NOTE: This string is in a file.
0
votes
4answers
115 views

Print text between tags (inclusive) if certain text is found

I've got a task to extract data from several Apache servers. The task is to print out: <Directory ...> ... </Directory> where +ExecCGI is located within. Let me give an example to ...
1
vote
2answers
2k views

Regular expression find 3 or 4 numbers

So, I have 50+ words and I have to match the numbers in them. These numbers can be 3 or 4 digit numbers. I think I tried every way there is, but nothing seems to work (I need to remember the number as ...
3
votes
5answers
154 views

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.
0
votes
1answer
262 views

Search for pattern across multiple files and replace a sub-part in all occurences

I am helping a friend with her thesis written in LaTeX and I need a quick solution for a "search and replace". Using a terminal in Linux, how can I find the following pattern: \caption{*\cite{*}} ...
1
vote
5answers
155 views

Extract one occurrence of a pattern from file

I have large file containing logs similar to one shown below. I would like to find all transactions(TR#) that were affected with the error. I need to extract one occurrence of each TR# ID. How could ...
-1
votes
2answers
146 views

Regular expressions in a shell [duplicate]

I have two questions about using regular expressions inside a shell. 1. Use of * According to wikipedia page on regular expressions: *: The asterisk indicates there is zero or more of the ...
0
votes
1answer
309 views

bash using grep and sed

This is for our weekly prac, no marking or grade (we don't even get the answers!) I'd really appreciate it if anyone has the time to help explain this exercise to me, as I'm trying to get this work ...
1
vote
2answers
407 views

Lazy regex using Bash

I'm trying to match just the text contained within the HTML tags using Bash's built-in regex function: string='<span class="circle"> </span>foo</span></span>' regex='<span ...
0
votes
1answer
47 views

Expansion of *,#,% - What do they mean? [duplicate]

for j in * .* ; do cp $j ../$name-S$i.gid/${j%%. * }$i.${j#*.} done Could someone tell me what this for loop does? What do *, % and # mean? ($name is a path of a directory in which there are ...
5
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2answers
2k views

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 ...
4
votes
2answers
1k views

How can I extract the numbers in the file using sed or any other tool?

I have a file that has this format [ 2014/05/01 10:48:26 | 13963 | DEBUG ] It took 11.16837501525879 seconds to complete the process So I have thousands of lines like this and I would like ...
3
votes
1answer
284 views

pcregrep newline lookbehind assertion bug?

Attempting to use pcregrep to print the first line after a blank line. For example, contents of file first line second line I need second line to be printed. Here are a few tests using the same ...
3
votes
3answers
424 views

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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votes
4answers
2k views

How to exclude directories from `ls -R` output?

If ls -aR | grep ":$" returns ./.hiddendir2: ./dir1: ./dir3: ./dir3/.hiddendir4: then how can you update the pattern given to grep so that you only get ./dir1: ./dir3: (note that the last ...
0
votes
4answers
331 views

How to extract the similarities between two strings

I have two strings in two different sentences: string 1: 30 mutation alanine for valine string 2: alanine at position 30 is there away to find the similarities between them as it is clear they ...
2
votes
2answers
124 views

Condition string matches reg.expression

So, in my script, I have to decide whether one of the parameters is a valid email address. I was trying, but it failed. if $maddr="^.$*\(@\)\(*\)\(.\)\(??*\)" then ... It's meant to mean: at least ...
0
votes
1answer
278 views

How many times does the same character occur twice in a row

My task is using grep to find how many times the same character occurs twice in a row. I was thinking about something like this but it isn`t working grep '[a-zA-z]{2}' *.txt | wc How can achieve ...
1
vote
1answer
95 views

Need to remove lines till a pattern is matched

My C code needs to decode some application data that were received over a socket by another application. I used the Wireshark to export the packets(many) into a C array. But the array carries all ...
4
votes
1answer
86 views

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, ...
2
votes
1answer
527 views

Regex doesn't work with grep

I have a string like this TEST="/dev/sda1 on /media/sda1 type vfat (rw,relatime,fmask=0000,dmask=0000,allow_utime=0022,codepage=cp437,iocharset=iso8859-1,quiet)" (Result from mount | grep sda1) ...
7
votes
1answer
190 views

Grep search returning a different line

This is my grep search grep 'Invoker_Slark*' true_pairscore.txt But it returns the line Invoker_Slardar. Even though the file contains Invoker_Slark. Why is that?
0
votes
1answer
587 views

Want to replace the words with space in multiple files using SED commmand [closed]

Want to replace the words with space in multiple files using SED commmand I have a word as 'Danny' with single quotes in many of my files in multiple directories which I want to change to 'Danny ...
3
votes
1answer
160 views

Merging text files based on their filename

I have hundred of files with the following format: 2013_01_19_xyxyxyx.txt 2013_01_19_xyxyxyx.txt 2014_03_21_xyxyxyx.txt 2014_03_21_zxzxzxz.txt 2014_03_22_abababa.txt 2014_03_22_cbcbcbc.txt etc. I ...
3
votes
2answers
361 views

Replacing 3 or more digits with equivalent number of *

I want to replace any 3 or more digit string in a text file with equivalent number of *.For example: abc-1234-45 --> abc-****-45 echo "abc-1234-45" | sed 's/[0-9]\{3,\}/*/' I tried this but it only ...
0
votes
1answer
3k views

grep: match pattern on a particular position

I need to match a pattern with grep, only if it starts at position 16. Let's suppose I want to match the string ' pattern' (starting with space). The following should match bla bla bla bla pattern ...
0
votes
5answers
2k views

bash event not found trying to match and exclude parenthesis in grep

In a very long line I'll summarize with: (foo),(bar,baz(word,right),(end) I want to print only: (bar,baz(word,right To match the second parenthesis, I exclude the word that follows the ...
3
votes
3answers
1k views

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. ...
6
votes
4answers
17k views

Grep for range of numbers [duplicate]

How would you search a log file for a date range? Log file looks like this: 01/14 00:00:01 INFO: received connect request from 10.10.10.10 I need to condense the log to 10 minutes starting ...
28
votes
1answer
2k views

Why does my regular expression work in X but not in Y?

I wrote a regular expression which works well in a certain program (grep, sed, awk, perl, python, ruby, ksh, bash, zsh, find, emacs, vi, vim, gedit, …). But when I use it in a different program (or on ...
0
votes
3answers
47 views

Grep lines from foe to foe2 (not included), regexp

The file is organized in entries of the form: foe, 1.... 2.... 3.... foe2, 1.... 2.... All sub-items begin with four spaces, and then text or number item. All entries like foe, begin ...
0
votes
1answer
80 views

How can I use gsub with a pattern? And how to tell it which file to awk?

I've read here that I can replace the values of all columns containing a particular text using awk -F'\t' -vOFS='\t' '{ gsub("CC", "C", $1) ; gsub("AA", "A", $1) ; print }' But where do I tell awk ...
3
votes
3answers
16k views

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 ...
3
votes
2answers
311 views

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 ...
4
votes
3answers
2k views

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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vote
1answer
505 views

awk date identification from input file

I currently have daily files that come in via FTP with incorrect dates in the first column of the file. I have figured out how to deduct one day to derive the correct date and print this to a new ...
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3answers
1k views

What does the dot in regex “^[A-Za-z]{2}[1-9]{2}.*” do?

I am very new with regexp. I would like to know the pattern defined by this regexp : ^[A-Za-z]{2}[1-9]{2}.* It starts with 2 alphabetic characters then 2 numeric characters then a . and * which is ...
2
votes
2answers
174 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
votes
4answers
960 views

regex matching with “locate”

I'm trying to use the locate command to find files in my home folder, however whenever I try and run this I get no results: locate -i -l 4 --regexp '^\/home\/jack\/[A-Za-z0-9\/\ ]*(My.)*$' I've ...
0
votes
3answers
705 views

How can I use grep to search a file for string combinations?

What I'm trying to do is use grep to search my Apache logs. What I want is to find is every entry from a certain IP address that also has .html or .php in the line. In other words, I want to see what ...
2
votes
1answer
782 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 ...
21
votes
6answers
7k views

Regex for all 10 letter words, with unique letters

I am trying to write a regex that will display all words that are 10 characters long, and none of the letters are repeating. So far, I have got grep --colour -Eow '(\w{10})' Which is the very ...