Tagged Questions

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

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3
votes
2answers
88 views

Extract specific set lines matching a rule

I have a large file with the logs as shown below. There are about 30000 instance of such events logged. I need to extract those lines beginning with RINGING and CLOSE (included) and which does NOT ...
4
votes
4answers
62 views

regexp which matches all tokens independent of order

I have a quick (and hopefully simple) question about regexps. I'm trying to think of a regexp which matches all of a set of tokens irrespective of order. So for example I have a file with the names ...
-1
votes
2answers
81 views

How to remove a newline character in a particular line through perl?

I want to remove a newline character in a particular line through perl one-liner command. Input: 1407233497,1407233514,bar 1407233498,1407233515,foo mingstats&fmt=n 1407233499,1407233516,foobar ...
0
votes
1answer
42 views

How can I parse my String using regular expression to get only certain number of matches? [closed]

I am currently using this following regular expression to split my String into groups. ^([a-zA-Z0-9]*)(\[([a-zA-Z0-9=]*)\]){0,1}@([a-zA-Z0-9]*)$ Pty[R=4]@ID I am getting four groups 1) Pty 2) ...
3
votes
1answer
60 views

Using sed to replace only the first two regex catches with different strings

So I'm trying to change two instances of a regex pattern to two different strings with sed like: sed -E "s/\\t([A-Za-z]|[-])+$/\\t`get_addr.py -1`/" /path/to/file.ext sed -E ...
1
vote
3answers
82 views

Find and change certain LaTeX coding in vim, using regular expressions?

How can I change the following LaTeX coding: \cite{1,3-7,9} to \cite{1,3,4,5,6,7,9} in vim? I would prefer to use regular expressions.
2
votes
3answers
246 views

Checking if an input number is an integer

I'm trying to check if an input is an integer and I've gone over it a hundred times but don't see the error in this. Alas it does not work, it triggers the if statement for all inputs ...
8
votes
7answers
408 views

How can I “merge” patterns in a single line?

I am doing grep and sed and I get 2 lines of a file that I am interested in. How can I get these lines in a single line ending with the new line character? Now I am getting: pattern1 pattern2 ...
4
votes
1answer
1k views

command: ls /etc | sort | grep d* is yielding no results but ls /etc | sort | grep p* lists entire directory

I am playing around with piping and grep tonight. I know that grep uses regex and that * means 0 or more occurrences of the preceding character. So the way I understand it is that if I do the ...
4
votes
5answers
206 views

Insert Lines after Multi-Line Regex Match

I've got an XML file I need to append to after a specific set of tags. Basically the file structure looks like this: <key>servers</key> <dict> ... Server Details ... </dict> ...
6
votes
1answer
526 views

find words with all vowels in order from a file

I have a large dictionary file with 300,000+ words in it and I'm trying to find all words with the vowels aeiou in that order and have only exactly 5 vowels. My current attempt does not seem to be ...
3
votes
1answer
37 views

Problem with regular expression in gawk ('\<' not working)

I am trying to get into bash a little bit. I was going through this guide but the second example in this subsection on gawk doesn't seem to work. The problem is this command: ls -l | awk ...
3
votes
1answer
51 views

Accept only y or yes with a one-line regular expression

I want to check if an input is y or yes (inputs in lowercase) and reject everything else What I have now is ^y[e]{'0,1'}[s]['0,1']$ But this accepts y, ye, ys, yes. I don't want ye and ys to be ...
2
votes
3answers
70 views

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 ...
2
votes
4answers
346 views

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 ...
0
votes
2answers
41 views

add bracket across numbers at only end of each line

I have a file having lines as: ram_reg_10/raja_reg_9/raghu_reg_8 abc_reg_4/bcd_reg_5 cad/pqr_reg_91 I want to convert string "_reg_number" into [number] at only last of every line in vi ...
5
votes
3answers
427 views

How to remove dot and space from beginning of filenames

I'm trying to change jpg files named with a dot and a space at the beginning and with a missing dot before the end (like this . Startjpg to Start.jpg The dot makes the files hidden from sed and ls ...
2
votes
3answers
348 views

Reverse match in sed, replace opposite of what was found

Say I have this output from my syslog, precalculated src_hash => 20 bytes @ 0x7f811c001e20 A6 2D E5 CD 2A BA F0 42 56 66 19 D4 61 1A E3 A0 .-..*..BVf..a... C7 5E 5F 77 ...
4
votes
6answers
220 views

Finding the number of time a particular number in a file where range also specified

I have a file with numbers separated by ,(comma). In between it also contains a number range like 300-400. Say for example I have a text file, namely testme.txt which looks like, ...
4
votes
2answers
77 views

sed regex issue

I'm trying to replace a string in a file: $RELEASE = '1234'; The whitespace between RELEASE and the = symbol could be either spaces OR tabs. The quotes around the version number could be either ...
4
votes
3answers
348 views

Regex alternation/or operator (foo|bar) in GNU or BSD Sed

I cannot seem to make it work. GNU sed documentation says to escape the pipe, but that doesn't work, nor does using a straight pipe without the escape. Adding parens makes no difference. $ echo ...
1
vote
4answers
476 views

Simple sed replacement of tabs mysteriously failing

This ought to be really simple, but for some reason it is not working: sed -i.bak -E 's/\t/ /' file.txt Instead of replacing tab characters, it's replacing t characters. I've tried every ...
2
votes
1answer
330 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 ...
5
votes
1answer
659 views

Why do I have to escape a “dot” twice?

I know that we can escape a special character like *(){}$ with \ so as to be considered literals. For example \* or \$ But in case of . I have to do it twice, like \\. otherwise it is considered ...
4
votes
3answers
163 views

Search and replace strings that are not substrings of other strings

I have a list of replacements like so: search_and -> replace big_boy -> bb little_boy -> lb good_dog -> gd ... I need to make replacements for the above, but at the same time avoid ...
2
votes
3answers
208 views

bash - extract filenames from html file containing multiple links

I have downloaded an html file autogenerated by a script on a webpage. The file contains multiple links, including links to images I am trying to extract the full names of the images, for example ...
0
votes
3answers
232 views

Grep finding phone numbers in files

How would I look for files in the /etc directory (but not subdirectories) that contain a standard United States long distance phone number, written using the pattern of 1-###-###-####, where each # is ...
1
vote
1answer
33 views

awk regex matches wrong?

Playing around with awk I noticed this behavior: [root@ror6ax3 ~]# grep open * | awk '$2 ~ /opens*/ {print $0}' install.log:Installing openldap-2.4.23-32.el6_4.1.x86_64 install.log:Installing ...
3
votes
1answer
63 views

How do back-references match in sed?

I found a one-line sed command on this site which removes duplicate entries in $PATH. There is one concept that I can't get my mind around. It uses saved matches in the match section to detect the ...
1
vote
1answer
84 views

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 ...
0
votes
0answers
14 views

Using regex in locate [duplicate]

I would like to search for both words pdf and hack in all filenames and their paths. The order of the two words doesn't matter. I use the command locate with a regex pattern: locate --regex ...
6
votes
5answers
243 views

Strategy to extract movies's name from this ununiform dataset?

I am working on a movie database problem to improve regular expressions, this is the problem I'm running into. My dataset looks like this: Movie Name (variable space and tabs) year Movie1(can ...
4
votes
3answers
510 views

Which regular expression methods to validate input could be used in shell scripting?

#!/bin/sh re="\/$" if [ $1 =~ $re ]; then echo "${ATTENTION_PREFIX}$1 DIRECTORY MAY NOT CONTAIN A \"/\" OR LITERAL SLASH!${ATTENTION_POSTFIX}" exit 1 fi Executing sudo file.sh ...
2
votes
1answer
54 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 ...
6
votes
3answers
443 views

Print all lines not containing punctuation

I want a regex pattern which can print all lines not containing punctuation : Input : .I am line 1 I am ! line 2 I am line (3) I am line 4 Output: ( should be) I am line 4 What I've tried so ...
2
votes
3answers
63 views

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 ...
2
votes
1answer
130 views

sed regexp HEX char

i have this string: echo -e "a12\x8fb12\x9f"|xxd 0000000: 6131 328f 6231 329f 0a a12.b12.. i want delete this sequence string 12\x9f and 12\x8f with sed. i can do it with this ...
2
votes
2answers
64 views

can regex capture groups be used in GNU find command?

With the GNU find command (GNU findutils 4.4.2), a regular expression can be used to search for files. For example: $ find pool -regextype posix-extended -regex ...
1
vote
4answers
272 views

Enclose multiple lines in quote Vim

I have blocks of the following form: String that is not supposed to be enclosed in quotes String that is supposed to be enclosed in quotes String that is not supposed to be enclosed in ...
2
votes
1answer
64 views

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, ...
1
vote
5answers
59 views

grep for text that may or may not be present

Lets say I have a file batman; robin; superman; password = ""; wonderwoman green lantern if I want to check if there is a password present, i.e there is something entered in the "" . here is an ...
-1
votes
2answers
89 views

How to get `expr match` to extract colon-delimited key-value pair?

Given: myvar="present-value: 1", I'd expect expr match "$myvar" '\([0-9]\)' to output 1. However, instead it outputs blank and exits with a non-zero status code indicating no match. How can I get it ...
3
votes
1answer
338 views

How to perform a multiline grep across multiple files?

I'm trying to grab this pattern wherever it occurs in multiple log files (Note:these patterns can vary greatly in size, i.e. the amount of Blahs): Found an txt File Blah Blah 10019874 ...
0
votes
3answers
62 views

Finding and replacing text inside awk block

I want to find and replace a value inside awk block. Here is a sample input file to my script P1 10,9:11/18013013582 ,10:1 ,167:0 ,487:5/E.164 11,9:15/310410532169026 ,10:60 ,167:0 ,487:4/IMSI ...
1
vote
2answers
378 views

Aix grep wildcard not working

I have a file called message that has the line CSC/UT/USA/WBIMB/SAP/orders05:orders05/ORDERS05/NONE/ORDRSP/758 I am doing a grep (Platform is AIX 6.1) grep ...
3
votes
3answers
134 views

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
vote
3answers
38 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
108 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
213 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
134 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 ...