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

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Pattern repetition and regexp

Take the pattern [UGLER]* Can the string UUG match against it? I mean to say, is repetition allowed?
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regular expressions with grep

I have this command right here: grep -B10 -A10 '14:14:50 {"channels":["/alerts/6979/new"],"data":"New alerts for unit 6979"}' mygateway.log Rather than searching for 14:14:50 I would like the 50 to ...
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Stuck in separating chars into strings in my approach. Found a working approach but can not understand it

I am trying to figure out how to break a string to be on character per line. I.e ahebhaaa to be: a h e b h a a a I tried: $ echo ahebhaaa | sed 's/\(.\)\(.\)/\1\n\2/g' I.e. my ...
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Why do I need to escape regex characters in sed to be interpreted as regex characters?

It seems e.g. cat sed_data.txt | sed 's/\b[0-9]\{3\}\b/NUMBER/g' that I must escape characters to form a regular expression. In this case I had to escape braces in order to be interpreted as a number ...
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vim search numbers containing specific number of digits

I need to find specific length numbers in a big document. I tried to use regex for this. For example, If I need to search for numbers with exactly 2 digits, I use /d/d (i.e. /d twice followed by a ...
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sed : Ignore line starting whitespace for match

I want to replace the default listening port of httpd to 9090. I can edit the line in httpd.conf file using below sed -i "/^Listen/c\Listen 9090" /etc/httpd/conf/httpd.conf But the line Listen 80 ...
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grep for an alphanumeric strings of any length with a colon on each side

How would you grep for an alphanumeric strings of 1 to 50 characters (ideally, any length would work too) with a colon on each side – a typical result would be all the lines containing the string ...
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How to insert both vimscript variable and string into vim search and replace

I've only just found out about Vimscript's existence as of today, so forgive me if this question is more basic than it seems, but I've been struggling to find an answer to this question for the better ...
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Aptitude regex engine

I was trying to lookup the versions of libdb in the debian archives with something like that: $ aptitude search '~S~ndev$(~nlibdb~(\d~|-~)!~v~rnative)' which didn't work as expected so I changed ...
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Match multiple regular expressions from a single file using awk

I'm trying to parse a HTML file using shell scripting. There are 4 different regular expressions that i need to catch: name= , age= , classs= , marks=. Using grep "name=\|age=\|class=\|marks=" ...
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How can I combine grep with file and extra regex

I have a file of strings in each line. For example: AAAAA BBBBB CCCCC etc I want to check each string one by one whether it exists in a series of files in a specific directory. I ...
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Regexp on data flow

I want to test if in my data flow, there is something, and do an exit code. I use gammu monitor, which provides a data flow, for example : [root@MYSERVER ~]# gammu monitor Press Ctrl+C to break... ...
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How to grep for pipe |

How can I grep for line containing pipe character | or for character >: files content: |this is test where is > this is none now what I need using grep command is grep -iE "<some ...
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Escaping * with Regular Expressions and Grep

I have a file that has unique lines that start with 2 stars (**). However when I run a grep command for grep \*\* fileName I get all of the lines in the file. This is very unusual, and what I ...
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Can tr work with regex?

I have a file like this: AAAA BBBB CCCC DDDD etc Words in separate lines. I want to add them quotes using tr. So I tried the following: 1) To add a quote in the start of each word ...
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Remove 2 and 3 newlines in a text file but not 1

I'm developing on a max osx 10.8 and have no preferences to which tool to use probably sed but it doesn't matter. Update after comment: The input file uses windows new lines if that's complicates ...
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Why is this line included in the `logcheck` report email?

In addition to the Debian provided rulesets, I have added a file /etc/logcheck/ignore.d.workstation/wpasupplicant.local (owner root:logcheck, mode 0644) to my newly installed logcheck setup. I have ...
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grep: display filename once, then display context with line numbers

Our source code has error codes scattered throughout. Finding them is easy with grep, but I'd like a bash function find_code that I can execute (eg. find_code ####) which will provide output along ...
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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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Pulling out keywords using standard command line utilities?

As an example, this is the pronunciation of "when" according to Wiktionary. enPR, IPA and X-SAMPA are different schemes for showing pronunciations. when:* {{a|US}} {{enPR|wĕn|hwĕn}}, ...
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Execute a command within 'sed'

I have a list of random memory addresses saved in a text file, and I need to sed them out, decode them, and save them back to my file. However, the decoding operation I'm trying to perform is handled ...
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Replace all occurences of \ except \N

I have a file like this: 1,2,subjects,\mat\hs,unix\,\Nato,\N,123,\N I want to replace all occurences of \ with #, except for \N, such that the output looks like this: ...
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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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Backreferencing with sed

I have a database containing a list of unsigned longs representing a bunch of memory addresses followed by an offset within two brackets (e.g. Mem[offset], 0x2322AD4[3]), and some other data. What I ...
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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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Forcing Bash to use Perl RegEx Engine

As you may already know, a lot of the features modern RegEx engines support (back referencing, lookaround assertions, etc.) are not supported by Bash RegEx engine. Following is a simple Bash script I ...
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What are the commands that you can use in the beginning of a sed command?

I initially learned to do sed search and replace like so: sed -e 's/<stuff>/<replacement>/' However I recently learned that these will do something different based on what command ...
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Change filename from lowercase to uppercase recursively

I have 1,000,000 files in some folders and subfolders. I want to rename them from lowercase to uppercase using shell commands. I don't want to modify the extension. only filename part. I have found ...
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using simple regex quantifier expression in grep

Does anyone know why ls | xargs -n 1 basename | grep -E '[0-9]{1}' does not only show occurrences of a single digit between 0-9? For example if I have: touch 1 touch 22 touch 333 touch test_file ...
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How can I grep for this or that (2 things) in a file?

I have a file that has "then"'s and "there"'s. I can $ grep "then " x.x x and then some x and then some x and then some x and then some and I can $ grep "there " x.x If there is no blob none ...
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Grep and regex, Why does the following return only a specific portion?

Why in the following: echo this is a line. | grep -o -E "[a-z]+\." The result is line. and not this is a line.? There is no word boundary or any other restriction on the regex.
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How to negate a regex inside another regex

That is, given a POSIX regex X, what POSIX regex is the complementary of X? (in a more detailed way: how to get regex X' that matches all strings that are not matched by X, but doesn't match any ...
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Removing second colon

Trying to create a simple script that lists mass mailing by the queue number that appears in /var/log/maillog. I'm starting off with this: [root@ditirdlns01 ~]# lsMails(){ grep -i ...
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extract part of string using sed

ls lib/oracle-11.2.0.3.0.txt | sed 's/lib.\([oracle.*]\)\.txt/\1/' It is giving the whole string instead of just oracle part until .txt What am I doing wrong? I can do it using awk as follows, but, ...
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Use grep with or [duplicate]

How do I search in a textfile with grep for the occurrence of a word or another word? I want to filter the apache log file for all lines including "bot" or "spider" cat ...
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Extract substring using regular expression on a Unix file

I have file with below contents . /ABC/RTE/AD_900_VOP_123/OPP /ABC/RTE/TRE/AD_900_VOP_145/BBB /ABC/RTE/AN_900_VFP_124/FBF /ABC/RTE/HD_900_FOP_153/WEW /ABD/RDV/AD_900_VOP_123/OPP ...
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syntax of ls --hide= and ls --ignore=

ls --hide and ls --ignore provides the possibility leave out files defined through regular expressions set after the --ignore= part. The latter makes sure that this option isn't turned off via -a, -A. ...
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Grep and sort several unsorted things in several lines (in one document)

I have a file with several unsorted things in one line which I want to put into a new file This is an example of part of the file I have: X1314448: SaMi|SM_g2554.t1 SaMi|SM_g5072.t1 Des|Des_g3808.t1 ...
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rsync exclude based on file size?

Is it possible to exclude files in rsync over a certain size (e.g. over 250 MB)? And what if I also want to exclude hidden files? How would I exclude all hidden files or directories (those that ...
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What is the meaning of this test expression []? [duplicate]

I've seen someone use command: ps -ef | grep [h]ttpd and Output is: apache 25125 31006 0 21:54 ? 00:00:00 /usr/sbin/httpd apache 26869 31006 0 22:04 ? 00:00:00 ...
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Using sed to find and replace complex string (preferrably with regex)

I have a file with the following contents: <username><![CDATA[name]]></username> <password><![CDATA[password]]></password> ...
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regex to match identifiers without double _

I want a regex to match identifiers consisting of letters, digits and _, without double underscores. My current attempt: ^(?!_)(?!.*?_$)[a-zA-Z][a-zA-Z0-9_]+$ Example: Abdfsdfsdf__ 1B2345_ ...
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find utility does not recognize bracket notation

I've two files in the current folder: submitWeb.m submit.m the following find does not show the two files: find . -regex .*submit\(Web\)?\.m But the above regex expression works fine in ...
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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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rsync certain files, excluding the rest, ignoring .svn/ directory, recursively

I'm using rsync to copy some files from a share to another. Recursively, I need to: Delete files at destination that were removed from the origin Only sync php and js files Exclude every other file ...
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How to find files with a certain subpath?

I need to find all xml-files that are placed in folders named config. Also config must be somewhere under a folder named trunk. For example, I am interested in all files like below: ...
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How to ask for specific parameters with grep?

I need to look in /usr/share/dict/words for a 5-letter word that starts with d or D, followed by a lowercase vowel, and ends with s. I have tried everything but to no avail.
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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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bash - reading user variable into bash script grep

I've tried every possible combination to get this bash script working. It's part of a larger script, and it basically prompts for a username (to check if it exists) and returns the appropriate ...
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Remove string from a particular field using awk/sed

I have a file (>80,000 lines) that looks likes this: chr1 GTF2GFF chromosome 1 249213345 . . . ID=chr1;Name=chr1 chr1 GTF2GFF gene 11874 14408 . + . ...