Regular expressions are a means of matching a pattern of characters within a string.
4
votes
1answer
602 views
What does \bi\b mean in a grep pattern?
What does this command do?
grep "\bi\b" linux.txt
What is it searching for?
4
votes
2answers
468 views
substrings and regexps
I have a string contained in a variable, and I want to extract substrings based on position relative to another substring. My solution seems to work unless the string is sent to a function as an arg. ...
4
votes
1answer
152 views
substituting third occurrence of a pattern using sed
Here is a sed command. I want to substitute third occurrence of 00 to 11
echo "0000000000000000" | sed -e 's/00/11/3'
The output is:
0000110000000000
But I thought output would be:
...
4
votes
3answers
2k views
grep: Trailing backslash
I want to do a grep for \resources\. How do I do this?
I've tried:
grep \resources\
grep \\resources\\
grep "\resources\"
grep "\\resources\\"
None of these work.
4
votes
2answers
262 views
How to find files with names having a long string after the first dot
My Samsung Galaxy S doesn't like files where the name contains a long string after the first dot. I guess some part of the software has a too short buffer for the file extension. How can I find all ...
4
votes
2answers
169 views
Regexp in .ssh/config
At work, I often have to log into hosts which follow a common naming scheme, e.g. qc01 - qc12, hc01 - hc10, and so on. All of these need to get the same config values in my laptop's .ssh/config. Of ...
4
votes
1answer
473 views
Renaming files to have lower case extensions with 'rename'
I'm trying to currently rename a large set of files and have been using quite kludgy methods to do so, such as:
rename 's:(.*)\.MOV:$1.mov:g' *.MOV
rename 's:(.*)\.JPG:$1.jpg:g' *.JPG
What I'd ...
4
votes
1answer
727 views
Print specific Exif image data values with exiv2
How do I print the image Exif date with a tool like exiv2?
My goal is to write the image year and month into separate variables. Do I really have to parse the output with regex or is there a ...
4
votes
1answer
170 views
Match word containing characters beyond a-zA-Z
To match a word one can use
\v(\w+)
From the vim help :h \w:
\w word character: [0-9A-Za-z_]
This works exactly as described in the manual. However, I want to
match words that contain ...
4
votes
1answer
249 views
Are there zero-width assertions in sed?
Is it possible to make lookahead or lookbehind zero-width assertions in sed? I want to emulate Perl's (?=) and family.
My sed is not GNU sed version 4.0.
4
votes
1answer
106 views
Using Regex in vim movment
Is there any way to use regular expression for movement in vim. For example,
I want to move my cursor to the first occurrence of the pattern abc. So can I do something analogous to fa but now a ...
4
votes
2answers
421 views
File manager which is able to filter using regular expressions
Is there any graphical file-manager which supports thumbnails for linux like thunar or nautilus, which allows me to filter a directory by a regular expression. For example typing /home/user/*tex ...
4
votes
1answer
505 views
Is there a tool in linux that allows multi-line regex expressions?
I'm wanting to find the results of a multi-line regular expression in linux. I tried grep, but like most linux utilities it's line based.
Is there something similar that allows me to search across ...
4
votes
2answers
607 views
Parsing XML from a shell script
I have a datafile like this:
<Key name="com.ahsay.afc.cpf.UserGroup" content="" allowMultiple="Y">
<Value name="rsv-id" inheritParentAttribute="Y" type="string" data="1328200856753" ...
3
votes
4answers
566 views
grep lines starting with “1” in Ubuntu
I try to search for lines that start with "1" using
ls -1 | grep ^1*
but it returns lines that do not start with 1. What I am missing here?
3
votes
2answers
187 views
Find and regex
What am I doing wrong with this find expression?
; touch ook ooks
; find . -name 'ook' -or -name 'ooks' -type f
./ook
./ooks
; find . -name 'ook[s]?' -type f
[returns nothing]
; echo $?
0
3
votes
5answers
308 views
changing pattern of a text file
A text file has contents something like
chair
table
pen
desk
Now i want it to be changed and stored in a variable say var as below
('chair','chair'),('table','table'),('pen','pen'),('desk','desk')
...
3
votes
3answers
321 views
Awk: check for length of field
In awk. I am working on Solaris 10, so it's probably an old(er) version of awk.
I came up with this rudimentary one-liner that works, at least for my particular input.
awk -F\; '$3 ~ /[ ...
3
votes
2answers
573 views
Grep 'OR' regex problem
I am trying to use grep with a regex to find lines in a file that match 1 of 2 possible strings. Here is my grep:
$ grep "^ID.*(ETS|FBS)" my_file.txt
The above grep returns no results. However if I ...
3
votes
5answers
165 views
Regex match in CLI
Is there something like a logical for the cli? I want to achieve this
mv -t newfolder *.(png|jpg)
so that alls jpg and png files are moved into newfolder. I know it could be done with
mv -t ...
3
votes
3answers
403 views
Extracting text from a text file in bash
I have a large text file that is all one line. In the text are several sections that looks like foo=12345 and I need to extract them all as separate lines, ignoring the rest of the file.
For ...
3
votes
4answers
3k views
Match regex in ksh
I am looking to do something like this in KSH:
if (( $var = (foo|bar)[0-9]*$ )); then
print "variable matched regex"
fi
Is it possible at all?
For the record I'm using Ksh Version M-11/16/88i ...
3
votes
4answers
1k views
Applying a regex to stdin
In programing we often see the use of Regular Expressions.
One of the most common forms is:
newText = text.replace( /regex/, 'replacementString' )
If stdin is text and stdout is newText, what ...
3
votes
2answers
113 views
Do procmail recipes have an alternator “or” operator?
Given the following procmail recipe:
:0:
* ^Subject:.*viagra.*
* ^From:.*viagra.*
/dev/null
Procmail would only delete emails that were both from viagra, and had viagra in the subject. Is it ...
3
votes
1answer
161 views
match files based on an md5 using find
I have a bunch js and css files in a directory. Some of them have been given a name based on an md5() of their content (looks like f10521a21bb013cb81e0909809818ad6.js). I'd like to match these files ...
3
votes
2answers
83 views
What is the usage of pattern before substitute command in sed
There is an example in this link about sed:
To delete the first number on all lines that start with a "#" use:
sed '/^#/ s/[0-9][0-9]*//'
What is the benefit of first pattern(/^#/)? It could be ...
3
votes
2answers
291 views
Find files starting with ~$ (MicroSoft Word Temp files)
For some reason my machine is full of M$ Word temporary files such as:
~$Filename.docx
~$AnotherFile.docx
Can someone suggest a find/regex command to search $HOME and delete them?
3
votes
3answers
1k views
AWK - how to reduce the greed of a regular expression?
I have an example:
echo "@article{gjn2010jucs, Author = {Grzegorz J. Nalepa}, " | awk '{ sub(/@.*,/,""); print }'
Is it possible to write a regular expression that selects the shorter pattern?
...
3
votes
4answers
220 views
Sort input file by the results of a regex
I'd like to sort a file based on the results of a regex expression. For example, if I have the following property declarations in Obj-C
@property (nonatomic, strong) id <AlbumArtDelegate, ...
3
votes
3answers
668 views
In a regular expression, which characters need escaping?
In general, which characters in a regular expression need escaping?
For example, the following is not syntactically correct:
echo '[]' | grep '[]'
grep: Unmatched [ or [^
This, however, is ...
3
votes
2answers
828 views
What regular expression engine type does bash use?
I use RegEx Buddy to prototype and debug my regular expressions. RegEx Buddy allows me to choose between a number of different regular expression engine types (.NET, Java, Perl, GNU BRE, GNU ERE, ...
3
votes
2answers
369 views
ANDed conditional using regexp and variables
I want to test whether a line, read in from a file, has a specific beginning AND an ending containing a word held in a variable. Here's some code:
The input file is:
line one
#; line two
#; line ...
3
votes
2answers
118 views
How to add a line in many files
I have many .html files and I need to add a meta tag after <head>'s start tag in each file.
How I can do that?
Can vim help me?
3
votes
1answer
624 views
escaping a single dot with double backslash - awk
"effective awk programming" book has an example on Field-Splitting. here is the example:
If you want fields to be separated by a literal period
followed by any single character, use ‘FS = ...
3
votes
2answers
565 views
simple command to strip header and footer from a file
I want a simple little command to strip an XML-Header and Footer from a file:
<?xml version="1.0" encoding="UTF-8"?>
<conxml>
<MsgPain001>
...
3
votes
2answers
325 views
Replace a substring of filenames in a directory
There exists a directory, which includes several levels of sub-directories. Under these directories, there are a set of files whose names include a common word, e.g, .cc. How can I replace the .cc ...
3
votes
2answers
154 views
Why isn't this sed regex matching?
I've recently started learning sed. I did
$seq 10 | sed '/[^049]/d'
I was expecting
4
9
10
as output. But I got
4
9
Where am I making mistake in understanding this regex?
3
votes
2answers
881 views
sed or tr one-liner to delete all numeric digits
So, I have this textfile, and it consists of mostly alphanumeric characters. It's a standard document. But since I copied it and pasted it from a PDF, there are page numbers in there. I don't much ...
3
votes
2answers
109 views
greedy and lazy regular expressions (comprehension question)
I am teaching myself regular expressions, and I got stuck at »greedy« vs. »lazy« repeatings.
What I found out so far is that
»greedy« means that the RegExp ...
3
votes
3answers
164 views
What does . match?
In working with regular expressions, I have been told that a dot character . will match everything.
Except for newlines \n.
Are there any other exceptions? What about the NUL character \0, or the ...
3
votes
2answers
3k views
sed one-liner to delete everything between a pair of brackets?
I am working with some text that is full of stuff between brackets [] that I don't want. Since I can delete the brackets myself, I don't need the one-liner to do that for me, but I do need a one-liner ...
3
votes
2answers
71 views
find command with regex {1,2}
I have been trying to create a find command string that will find all files that end with a number 1-99 but exclude all others.
e.g. I want to find myfile1 myfile99 but not myfile456 and not ...
3
votes
1answer
534 views
Substituting the first occurrence of a pattern in a line, for all the lines in a file with sed
Is it possible to do it in one liner?
I have an output like this:
"First line" - Description
" Second line" - Description
"Third line" - Description
" Fourth line" - Description
This input ...
3
votes
1answer
128 views
Character classes: construct my own
I want to construct my own character class in a script, then modify (and use) it, for example:
[:myclass:] contains a, *, \n (as linefeed) and [WHITESPACE].
I want to add all characters to ...
3
votes
2answers
506 views
Wget - Mirroring a full website with requisites on differents hosts
I am trying to make a full static copy of a wordpress website with wget to be browsed without any network connection (all links and images must be converted).
The different requisites for the pages ...
3
votes
1answer
262 views
Ex and Vi: buffers and regexes
I want to put regex matches to buffer but cannot get even simpler example y :.put myNewBuffer return msg [line] [put] [buffer] working ie how to put something to buffer?
So to regular expressions ...
3
votes
0answers
130 views
How to use regrex with AWK for string replacement in this example? [duplicate]
Possible Duplicate:
How to use regrex with AWK for string replacement in this example?
Suppose there is some text from a file:
(bookmarks
("Chapter 1 Introduction 1" "#1"
("1.1 Problem ...
2
votes
4answers
894 views
How to insert the content of a file into another file (if regexp) in shell/perl
File1 Contents:
line1-file1 "1"
line2-file1 "2"
line3-file1 "3"
line4-file1 "4"
File2 Contents:
line1-file2 "25"
line2-file2 "24"
Pointer-file2 "23"
...
2
votes
2answers
463 views
sed, grep, or tr command that returns only Latin characters from a UTF-8 file
I am working with the text of the 300 tang poems, which unfortunately is a single file containing both Chinese and English. Since I am interested in 'extracting' the English, I hope to use sed, ...
2
votes
3answers
254 views
sed one-liner to delete any line that begins with a digit
Pretend I am working with this file.
The beginning of the first visible line is obscured, so ignore that. 43 is the beginning of the next line, and that line would be deleted.
The next line (which ...
