The other answers here show some ways you can contort different varieties of regex to do this, although I think it does turn out that the answer is, in general, “don’t do that”. Such regular expressions are much harder to read and probably slower to execute than just combining two regular expressions using the boolean logic of whatever language you are using. If you’re using the `grep` command at a unix shell prompt, just pipe the results of one to the other:

    grep &quot;alpha&quot; | grep -v &quot;beta&quot;

I use this kind of construct all the time to winnow down excessive results from `grep`. If you have an idea of which result set will be smaller, put that one first in the pipeline to get the best performance, as the second command only has to process the output from the first, and not the entire input.

Well as we&#39;re all posting answers, here it is in awk ;-)

    awk &#39;/x/ &amp;&amp; !/y/&#39; infile

I hope this helps.

`^((?!beta).)*alpha((?!beta).)*$` would do the trick I think.

I&#39;m pretty sure this isn&#39;t possible with true regular expressions. The `[^y]*x[^y]*` example would match yxy, since the * allows zero or more non-y matches.

EDIT:

Actually, this seems to work: `^[^y]*x[^y]*$`. It basically means &quot;match any line that starts with zero or more non-y characters, then has an x, then ends with zero or more non-y characters&quot;.

Try using the excludes operator: `[^y]*x[^y]*`

**Simplest solution:**

    grep &quot;alpha&quot; * | grep -v &quot;beta&quot;

Please take care of gaps and double quotes.

I&#39;m running a dialog box upon user leaving the page.  The only thing is it runs for 1 sec and disappears?  I know it has to do with `bind(&#39;beforeunload&#39;)`, but the dialog dies sooner than you can read it.

How do I stop this from happening?

    $(document).ready(function() {	
						   
		// Append dialog pop-up modem to body of page
		$(&#39;body&#39;).append(&quot;&lt;div id=&#39;confirmDialog&#39; title=&#39;Confirm&#39;&gt;&lt;p&gt;&lt;span class=&#39;ui-icon ui-icon-alert&#39; style=&#39;float:left; margin:0 7px 20px 0;&#39;&gt;&lt;/span&gt;Are you sure you want to leave &quot; + brandName + &quot;? &lt;br /&gt; Your order will not be saved.&lt;/p&gt;&lt;/div&gt;&quot;);
		
		// Create Dialog box
		$(&#39;#confirmDialog&#39;).dialog({
		  autoOpen: false,
		  modal: true,
		  overlay: {
			backgroundColor: &#39;#000&#39;,
			opacity: 0.5
		  },
		  buttons: {
			&#39;I am sure&#39;: function() {
			  var href = $(this).dialog(&#39;option&#39;, &#39;href&#39;, this.href);
			  window.location.href = href;
			},
			&#39;Complete my order&#39;: function() {
			  $(this).dialog(&#39;close&#39;);
			}
		  }
		});
		
		// Bind event to Before user leaves page with function parameter e
		$(window).bind(&#39;beforeunload&#39;, function(e) {	
			// Mozilla takes the
			var e = $(&#39;#confirmDialog&#39;).dialog(&#39;open&#39;).dialog(&#39;option&#39;, &#39;href&#39;, this.href);
			// For IE and Firefox prior to version 4
			if (e){
				$(&#39;#confirmDialog&#39;).dialog(&#39;open&#39;).dialog(&#39;option&#39;, &#39;href&#39;, this.href);
			}
			// For Safari
			e.$(&#39;#confirmDialog&#39;).dialog(&#39;open&#39;).dialog(&#39;option&#39;, &#39;href&#39;, this.href);
		});	
			
		// unbind function if user clicks a link
		$(&#39;a&#39;).click(function(event) {
			$(window).unbind();
		 	//event.preventDefault();
			//$(&#39;#confirmDialog&#39;).dialog(&#39;option&#39;, &#39;href&#39;, this.href).dialog(&#39;open&#39;);
		});
		
		// unbind function if user submits a form
		$(&#39;form&#39;).submit(function() {
			$(window).unbind();
		});
    });

Dialog box runs for 1 sec and disappears?

Is this a proper way to declare immutable structs?

    public struct Pair
    {
        public readonly int x;
        public readonly int y;
        
        // Constructor and stuff
    }

I can&#39;t think of why this would run into problems, but I just wanted to ask to make sure.

In this example, I used ints. What if I used a class instead, but that class is also immutable, like so? That should work fine too, right?

    public struct Pair
    {
        public readonly (immutableClass) x;
        public readonly (immutableClass) y;
        
        // Constructor and stuff
    }

(Aside: I understand that using Properties is more generalizable and allows changing, but this struct is intended literally to just store two values. I&#39;m just interested in the immutability question here.)

Does using public readonly fields for immutable structs work?

I need a single-pass regex for unix grep that contains, say alpha, but does not contain beta.

    grep &#39;alpha&#39; &lt;&gt; | grep -v &#39;beta&#39;

Unix grep regex containing &#39;x&#39; but not containing &#39;y&#39;

I need a single-pass regex for unix grep that contains, say alpha, but does not contain beta.
<pre><code class="hljs language-perl">grep 'alpha' &#x3C;> | grep -v 'beta'
</code></pre>

&gt; **Possible Duplicate:**  
&gt; [Fastest method to replace all instances of a character in a string](https://stackoverflow.com/questions/2116558/fastest-method-to-replace-all-instances-of-a-character-in-a-string)  

&lt;!-- End of automatically inserted text --&gt;

How can you replace all occurrences found in a string?

If you want to replace all the newline characters (\n) in a string..

This will only replace the first occurrence of newline

    str.replace(/\\n/, &#39;&lt;br /&gt;&#39;);

I cant figure out how to do the trick?

replace all occurrences in a string

I was wondering If I could get a regular expression which will match a string that only has alphabetic characters, and that alone.

Regular Expression to match only alphabetic characters

My question is a simple one, and it is about regular expression escaping. Do you have to escape a forward slash `/` in a regular expression? And how would you go about doing it?

Escaping a forward slash in a regular expression

What is the type of the compiled regular expression in python?

In particular, I want to evaluate

    isinstance(re.compile(&#39;&#39;), ???)

to be true, for introspection purposes.

One solution I had was, have some global constant `REGEX_TYPE = type(re.compile(&#39;&#39;))`, but it doesn&#39;t seem very elegant.

**EDIT:** The reason I want to do this is because I have list of strings and compiled regex objects. I want to &quot;match&quot; a string against list, by

 - for each string in the list, try to check for string equality.
 - for each regex in the list, try to check whether the string matches the given pattern.

and the code that I came up with was:

    for allowed in alloweds:
        if isinstance(allowed, basestring) and allowed == input:
            ignored = False
            break
        elif isinstance(allowed, REGEX_TYPE) and allowed.match(input):
            ignored = False
            break



Type of compiled regex object in python

I want to create a regex that removes all non-alphanumber characters but keeps spaces. This is to clean search input before it hits the db. Here&#39;s what I have so far:

    @search_query = @search_query.gsub(/[^0-9a-z]/i, &#39;&#39;)

Problem here is it removes all the spaces. Solutions on how to retain spaces?

How do I strip non alphanumeric characters from a string and keep spaces?

I’m trying to count a particular word occurrence in a whole directory. Is this possible?

Say for example there is a directory with 100 files all of whose files may have the word “aaa” in them. How would I count the number of “aaa” in all the files under that directory?

I tried something like:

     zegrep &quot;xception&quot; `find . -name &#39;*auth*application*&#39; | wc -l 

But it’s not working.

How to count occurrences of a word in all the files of a directory?

I am using the following to search a directory recursively for specific string and replace it with another:

    grep -rl oldstr path | xargs sed -i &#39;s/oldstr/newstr/g&#39;

This works okay. The only problem is that if the string doesn&#39;t exist then `sed` fails because it doesn&#39;t get any arguments. This is a problem for me since i&#39;m running this automatically with ANT and the build fails since `sed` fails.

Is there a way to make it fail-proof in case the string is not found?

I&#39;m interested in a one line simple solution I can use (not necessarily with `grep` or `sed` but with common unix commands like these).


Using grep and sed to find and replace a string

I&#39;m on EC2 instance. So there is no GUI.

    $pip install selenium
    $sudo apt-get install firefox xvfb

Then I do this:

    $Xvfb :1 -screen 0 1024x768x24 2&gt;&amp;1 &gt;/dev/null &amp;

    $DISPLAY=:1 java -jar selenium-server-standalone-2.0b3.jar
    05:08:31.227 INFO - Java: Sun Microsystems Inc. 19.0-b09
    05:08:31.229 INFO - OS: Linux 2.6.32-305-ec2 i386
    05:08:31.233 INFO - v2.0 [b3], with Core v2.0 [b3]
    05:08:32.121 INFO - RemoteWebDriver instances should connect to: http://127.0.0.1:4444/wd/hub
    05:08:32.122 INFO - Version Jetty/5.1.x
    05:08:32.123 INFO - Started HttpContext[/selenium-server/driver,/selenium-server/driver]
    05:08:32.124 INFO - Started HttpContext[/selenium-server,/selenium-server]
    05:08:32.124 INFO - Started HttpContext[/,/]
    05:08:32.291 INFO - Started org.openqa.jetty.jetty.servlet.ServletHandler@1186fab
    05:08:32.292 INFO - Started HttpContext[/wd,/wd]
    05:08:32.295 INFO - Started SocketListener on 0.0.0.0:4444
    05:08:32.295 INFO - Started org.openqa.jetty.jetty.Server@1ffb8dc


Great, everything should work now, right?

When I run my code:

    from selenium import webdriver
    from selenium.common.exceptions import NoSuchElementException
    from selenium.webdriver.common.keys import Keys
    
    browser = webdriver.Firefox() 
    browser.get(&quot;http://www.yahoo.com&quot;) 

I get this:

    Error: cannot open display: :0




How do I run Selenium in Xvfb?

How can I list all Java processes in bash?
I need an command line. I know there is command `ps` but I don&#39;t know what parameters I need to use.

List of Java processes

While having a cygwin installed in windows gives most of unix command, still i was wondering how to search multiple filetypes in one command using windows &quot;find&quot; command.  
ie:   `find . -name *.cpp -o -name *.h -o -name *.java`

The above command gives me a list of all cpp, h &amp; java, what will be the equivalent using the windows find?

Windows equivalent for Unix find command to search multiple file types

I&#39;m grepping through a large pile of code managed by git, and whenever I do a grep, I see piles and piles of messages of the form: 

    &gt; grep pattern * -R -n
    whatever/.git/svn: No such file or directory

Is there any way I can make those lines go away? 

How can I have grep not print out &#39;No such file or directory&#39; errors?

How do I grep for lines that contain two input words on the line?  I&#39;m looking for lines that contain both words, how do I do that? I tried pipe like this:

    grep -c &quot;word1&quot; | grep -r &quot;word2&quot; logs

It just stucks after the first pipe command.

Why?

How to grep for two words existing on the same line?

I want to write in a bash script a piece of code that checks if a program is already running.
I have the following in order to search whether bar is running

     foo=`ps -ef | grep bar | grep -v grep`

The

     grep -v grep

part is to ensure that the &quot;grep bar&quot; is not taken into account in ps results

When bar isn&#39;t running, foo is correctly empty. But my problem lies in the fact tha the script has

     set -e

which is a flag to terminate the script if some command returns an error.
It turns out that when bar isn&#39;t running, &quot;grep -v grep&quot; doesn&#39;t match with anything and grep returns an error. I tried using -q or -s but to no avail.

Is there any solution to that? Thx

Prevent grep returning an error when input doesn&#39;t match

I&#39;m trying to write a regular expression to match anything that isn&#39;t &quot;foo&quot; and &quot;bar&quot;.  I found how to match anything but one word at https://stackoverflow.com/questions/406230/regular-expression-to-match-string-not-containing-a-word but I&#39;m not very skilled with regex and am unsure of how to add a second word to this critera.

Any help would be most appreciated! 


CLARIFICATION:

I wanted to match on anything that wasn&#39;t EXACTLY foo or bar.

Regex to match anything but two words

Assume the following strings:

    aaa bbb ccc
    bbb aaa ccc

I want to match `aaa` as long as it is not at the start of the string. I&#39;m trying to negate it by doing something like this:

    [^^]aaa

But I don&#39;t think this is right. Using `preg_replace`.

Regex: match pattern as long as it&#39;s not in the beginning

Below is the content:

    Subject:
        Security ID:        S-1-5-21-3368353891-1012177287-890106238-22451
        Account Name:       ChamaraKer
        Account Domain:     JIC
        Logon ID:       0x1fffb

    Object:
        Object Server:  Security
        Object Type:    File
        Object Name:    D:\ApacheTomcat\apache-tomcat-6.0.36\logs\localhost.2013-07-01.log
        Handle ID:  0x11dc

I need to capture the words after the `Object Name:` word in that line. Which is `D:\ApacheTomcat\apache-tomcat-6.0.36\logs\localhost.2013-07-01.log`.

How can I do this?

`^.*\bObject Name\b.*$` matches - Object Name





Content Type	Original Author	Original Content on Stackoverflow
Question	Wilderness	View Question on Stackoverflow
Solution 1 - Regex	nohat	View Answer on Stackoverflow
Solution 2 - Regex	shellter	View Answer on Stackoverflow
Solution 3 - Regex	Mr47	View Answer on Stackoverflow
Solution 4 - Regex	Shea Levy	View Answer on Stackoverflow
Solution 5 - Regex	sblundy	View Answer on Stackoverflow
Solution 6 - Regex	Deepshikha Satish	View Answer on Stackoverflow

Unix grep regex containing 'x' but not containing 'y'

Regex Problem Overview

Regex Solutions

Solution 1 - Regex

Solution 2 - Regex

Solution 3 - Regex

Solution 4 - Regex

Solution 5 - Regex

Solution 6 - Regex

Does using public readonly fields for immutable structs work?

Dialog box runs for 1 sec and disappears?

Attributions