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

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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 ...
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4answers
140 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
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3answers
202 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
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1answer
230 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 ...
20
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6answers
4k 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 ...
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2answers
46 views

How can I append multiple extensions to a string with sed?

I want to create a script that will let me download images from entire subreddits at once, but I'm currently stuck on just getting the links right (one problem at a time! ^^). Anyway, since I can't ...
0
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1answer
48 views

Piped search queries in vim or less

I would like to be able to search a log file for lines that being with ^2014-02-18 15:30:[0-9:,]* and have UserName:someguy much later in the same line. I am sure I could do a regex to include any ...
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171 views

Regex `/pattern/g` and ed `:g/pattern/`: which came first, and why `g`?

The g option (e.g. s/pattern/replacement/g) for many tools that use regex-style pattern matching and the :g command in ed, ex, vi, and vim have pretty similar usage and meaning: match the given regex ...
2
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1answer
122 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 ...
4
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4answers
912 views

Print line after nth occurrence of a match

I am looking to display the line 4598 in the following file. Effectively I want to display the line AFTER the nth occurrence of a match. In this case, the line after the 3rd occurrence of <Car>. ...
2
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1answer
174 views

Counting consecutive repetitions of a specific character (e.g. ,)

Say I have a file with lines like the two following: foo,bar,,baz,xy foo,,bar,baz,xy,, I would like to count how many times I have ,, (two consecutive commas surrounded by any other character) in ...
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1answer
28 views

Finding all kinds of extensions referenced in a html file

Here is my problem statement : There is a folder with many html and text files. I need to recursively go through each one of them and find all kinds of file extensions referenced in these html/text ...
1
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1answer
90 views

Why isn't sed using the extended regex mode by default?

I am using sed. I was using a regex that was correct as far as I could see but sed did not do anything. Turns out that I was using \s+ which sed can not understand (?) and when I switched to [ ]+ it ...
2
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2answers
58 views

Why don't I need to escape a character class in sed but I need to escape the rest?

I am confused with sed. I had a file with the following contents: [ 2014/02/10 14:45:15 | INFO ] Saving data for customer: 273667 [ 2014/02/10 14:45:15 | INFO ] Saving data for customer: ...
2
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2answers
182 views

SED change only start of line and preserve end of line

Basically I have a situation where I frequently need to modify my hosts file to access different servers at my workplace. In an attempt to automate the process. I've been trying to use sed to make the ...
1
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1answer
176 views

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 ...
0
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1answer
63 views

All occurrences of a regex get removed without using the “global” modifier

I have the following text in the file sentence.txt Linux refers to the family of Unix-like computer operating systems that use the Linux kernel. Linux can be installed on a wide variety of ...
2
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1answer
114 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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282 views

Find duplicate file names with specific matching pattern

I have a folder with some files (snippet of the contents of the folder) PAT1.URGRSVP.50.WR786842JOB11632.WRS20140.FILE0005.DAT PAT1.URGRSVP.50.WR786842JOB11643.WRS20140.FILE0003.DAT ...
11
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4answers
6k views

How can I “grep” patterns across multiple lines?

It seems I am misusing grep/egrep. I was trying to search for strings in multiple line and could not find a match while I know that what I'm looking for should match. Originally I thought that my ...
4
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1answer
140 views

Why does grep treat '[D]ebug' string differently?

I've created simple text file named "T" to test the unusual behavior of grep: 1 Debug 2 debug 3 determined 4 Determined Tried different syntax: $ grep De T 1 Debug ...
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4answers
2k views

Regular expression in Bash to validate IP-address

In my Python script i have a regular expression for searching IP-addresses like 0.0.0.0-255.255.255.255 in a file, it looks like this: ...
0
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1answer
270 views

How do I join the next line when a line matches a regex for whole document in VI?

As title, for example, I have lines like abcdefg join! abcdef no join abcdefg join! If a line matches regex ^a.+g$ then I would like them to be joined, so it would be: abcdefgjoin! abcdef no join ...
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6answers
686 views

Replace a character except last x occurences

I have a file that has a bunch of hostnames correlated with IPs that looks like this: x-cluster-front-1 192.168.1.2 x-cluster-front-2 192.158.1.10 y-cluster-back-1 10.1.11.99 y-cluster-back-2 ...
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2answers
64 views

How does “$” work in “apt-cache search something$”

I understand that $ apt-cache search package_name will search for matches in names and descriptions. But how does this work? $ apt-cache search package_name$ For example, $ apt-cache search ...
2
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1answer
74 views

using grep --perl-regexp

this is a sample output of ls $ ls -lAF -rw------- 1 martin martin 168 Jan 25 23:26 aaa -rw------- 1 martin martin 168 Jan 25 23:26 bbb -rw------- 1 martin martin 168 Jan 25 23:26 ccc I would ...
5
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1answer
725 views

Using Modifiers of Perl-compatible Regex (PCRE) in grep

According to grep --help and man grep, we can use the -P option in order to interpret the pattern as a Perl regular expression (PCRE, to be precise), instead of the default POSIX basic regular ...
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316 views

How to get numbers by using regular expression, but only last one

In this example I can get 00. expr match "00 foo 99.jpg" '[^0-9]*\([0-9]\+\).*$' I want to know how to get last number from string, in this case 99 by using regular expression. The string may ...
3
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1answer
143 views

Expanding comma-separated list into separate lines

I have a file with some data in this form: Prefix text: First Name, Second Name, Third-- The prefix differs by line. The number of names varies from one to several. The suffix (-- in the example) ...
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1answer
31 views

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 ...
4
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Why sed prints first string from file even if it's failed to find matching groups

I'm trying to write sed expression which will extract matching groups from file. E.g. I have .cue sheet and I want to extract it's genre tag. It has following format: $ cat file.cue | grep GENRE REM ...
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2answers
178 views

Why is my grep + regex not working?

I recently decided that enough was enough -- I was going to learn to use grep fluently. It's been all of three hours and I'm already stumped by this toy problem. I'm currently syncing a RAID5 array, ...
5
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3answers
171 views

The ERE regex to split() string between a delimiter and end-of-word

I'm using a long gawk 3.1.6 script to do a complex conversion of Zim markdown text into GtkDialog code and am stuck on the following problem... Sample ASCII input... [[link|label label]] [[link]] ...
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1answer
180 views

extracting ip address from a file [closed]

I'm trying to extract all the IP address from a file. FILE *>i85.95.2.160/29 172.16.24.4 0 200 0 64515 4445 15412 i *>i85.112.80.0/28 172.16.24.4 0 200 ...
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1answer
134 views

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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1k views

Using a variable in a regex

How can I use a variable string in a regular expressions while read line do if [[ line =~ *"$key"* ]]; then echo line fi done < "$filename" $key is a string ...
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2answers
1k views

Differing outputs of the commands “ls .*” and “ls *.”

The command ls .* when run gives as output the following : All the files in the current directory starting with a . (hidden files) All the files in the hidden directories present in the ...
1
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2answers
48 views

use search result in replace statement with vim substitute

I know this is gonna be a stupid question, but I've tried here, google and the official documentation. I've got a file with a whole heap of words of the form 'foo' and i want to change them to ...
0
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3answers
161 views

Ignore lines containing a capital letter

Why does the following command still return some lines containing a capital letter? aspell dump master | grep ozz | grep -v '[^A-Z]'
2
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2answers
146 views

Understanding -regex with GNU find

Background I have what I think should be a simple case. I want to find all files with "cisco" in the name and do something with those files (via xargs). Finding files with ls Before I use xargs, ...
3
votes
1answer
248 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 ...
2
votes
1answer
1k 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 ...
0
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2answers
233 views

bash script, printing multiple lines that matching to a specific patern

I have a log file and I'm making a script to do some actions. An action is to print a specific area of the log. Every block at the log starts with a specific time stamp and inside the block may have ...
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1answer
83 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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755 views

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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2answers
2k views

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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2answers
710 views

“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 ...
0
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2answers
148 views

Regex and patterns on a ksh command line

I'm wondering what's the difference between using * and .* in a regex string. I guess, * stands for "0 to n characters" but I don't see what .* stands for. For example, what is the difference ...
3
votes
2answers
44 views

Extracting just a single group from a regular expression

I am trying to get a list of numbers from some hacked-together log files using zgrep. So, I am using: zgrep -ie "total time: .* ms" * This returns the whole line that I care about. I'd just like ...
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142 views

Ensure /etc/export contains rule using bash

What's a working example of modifying /etc/export using bash? Example: I want to ensure the following rule is present and valid: /export/home 2400:123::/32(rw,no_root_squash) And it should: Add ...