Try `M-x query-replace-regexp` with `&quot;&lt;\([^&gt;]+\)&gt;&quot;` as the search string and `&quot;&lt;\,(downcase \1)&gt;&quot;` as the replacement.

This should work for Emacs 22 and later, see this [Steve Yegge blog post][1] for more details on how Lisp expressions can be used in the replacement string.

For earlier versions of Emacs you could try something like this:

    (defun tags-to-lower-case ()
      (interactive)
      (save-excursion
        (goto-char (point-min))
        (while (re-search-forward &quot;&lt;[^&gt;]+&gt;&quot; nil t)
          (replace-match (downcase (match-string 0)) t))))




  [1]: http://steve-yegge.blogspot.com/2006/06/shiny-and-new-emacs-22.html

I realize this question is ancient, but I just discovered how to do this in Emacs **before** version 22 (my version is 21.3.1) without the need for defining a custom Lisp function: use `M-x query-replace-regexp-eval` (mentioned at the top of [this Emacs wiki page][1]) with `&lt;\([^&gt;]+\)&gt;` as the search string and `(concat &quot;&lt;&quot; (downcase \1) &quot;&gt;&quot;)` as the replacement.

This should work with any replacement string that can be defined as a concatenation of parts, including captured groups not modified by any function.  For example:

    &lt;BarFoo baz=&quot;Quux&quot;&gt;

can have just the tag name downcased:

    &lt;barfoo baz=&quot;Quux&quot;&gt;

by using search string `&lt;\([A-Za-z]+\)\([^&gt;]*\)&gt;` and replacement `(concat &quot;&lt;&quot; (downcase \1) \2 &quot;&gt;&quot;)` (which also works on OP&#39;s example that looks like a tag with no attributes).


  [1]: https://www.emacswiki.org/emacs/ReplaceRegexpWithLispExpressions

When using evil, you can simply do `:%s/&lt;\([^&gt;]+\)&gt;/&lt;\L\1&gt;`

`\L` is responsible for lowercasing all following letters, this should also work for `query-replace-regexp`.

I have not found documentation around Emacs for that, but it seems to match this list: https://www.boost.org/doc/libs/1_44_0/libs/regex/doc/html/boost_regex/format/perl_format.html

- **Is PHP (as of 5.2) thread-safe on Linux/UNIX?**
- **Would it be possible to use it with Apache Worker-MPM or Event-MPM?**

The facts I gathered so far are inconclusive:

- Default binaries included in most distributions have ZTS disabled, so I&#39;m aware, that I&#39;d have to recompile them.
- In theory Zend Engine (core PHP) with ZTS enabled is thread-safe.
- It&#39;s said that some modules might not be thread-safe, but I haven&#39;t found any list of modules that are or that are not.
- [PHP FAQ][1] states pretty much same as above.

What&#39;s your experience?

It&#39;s not only about [segmentation faults][2] (&quot;access violations&quot; in Windows nomenclature). There is a lot more to [thread safety][3].

  [1]: http://www.php.net/manual/en/faq.installation.php#faq.installation.apache2
  [2]: http://en.wikipedia.org/wiki/Segmentation_fault
  [3]: http://en.wikipedia.org/wiki/Thread_safe


Is PHP thread-safe?

Is it possible to do a select ( or insert) statement across different databases that are located on the same server? If yes, how?

Select columns across different databases

Every once in a while I want to replace all instances of values like:

    &lt;BarFoo&gt;

with

    &lt;barfoo&gt;

i.e. do a regular expression replace of all things inside angle brackets with its lowercase equivalent.

Anyone got a nice snippet of Lisp that does this? It&#39;s safe to assume that we&#39;re dealing with just ASCII values. Bonus points for anything that is generic enough to take a full regular expression, and doesn&#39;t just handle the angle brackets example. Even more bonus points to an answer which just uses `M-x query-replace-regexp`.

Thanks,

Dom

Emacs: regular expression replacing to change case

Every once in a while I want to replace all instances of values like:
<pre><code class="hljs language-php-template">&#x3C;BarFoo>
</code></pre>
with
<pre><code class="hljs language-php-template">&#x3C;barfoo>
</code></pre>
i.e. do a regular expression replace of all things inside angle brackets with its lowercase equivalent.
Anyone got a nice snippet of Lisp that does this? It's safe to assume that we're dealing with just ASCII values. Bonus points for anything that is generic enough to take a full regular expression, and doesn't just handle the angle brackets example. Even more bonus points to an answer which just uses <code>M-x query-replace-regexp</code>.
Thanks,
Dom

One mistake I see people making [over][1] and [over again][2] is trying to parse XML or HTML with a regex.  Here are a few of the reasons parsing XML and HTML is hard:

People want to treat a file as a sequence of lines, but this is valid:

    &lt;tag
    attr=&quot;5&quot;
    /&gt;

People want to treat &lt; or &amp;lt;tag as the start of a tag, but stuff like this exists in the wild:

    &lt;img src=&quot;imgtag.gif&quot; alt=&quot;&lt;img&gt;&quot; /&gt;

People often want to match starting tags to ending tags, but XML and HTML allow tags to contain themselves (which traditional regexes cannot handle at all):

    &lt;span id=&quot;outer&quot;&gt;&lt;span id=&quot;inner&quot;&gt;foo&lt;/span&gt;&lt;/span&gt; 

People often want to match against the content of a document (such as the famous &quot;find all phone numbers on a given page&quot; problem), but the data may be marked up (even if it appears to be normal when viewed):

    &lt;span class=&quot;phonenum&quot;&gt;(&lt;span class=&quot;area code&quot;&gt;703&lt;/span&gt;)
    &lt;span class=&quot;prefix&quot;&gt;348&lt;/span&gt;-&lt;span class=&quot;linenum&quot;&gt;3020&lt;/span&gt;&lt;/span&gt;

Comments may contain poorly formatted or incomplete tags:

    &lt;a href=&quot;foo&quot;&gt;foo&lt;/a&gt;
    &lt;!-- FIXME:
        &lt;a href=&quot;
    --&gt;
    &lt;a href=&quot;bar&quot;&gt;bar&lt;/a&gt;

What other gotchas are you aware of?

  [1]: https://stackoverflow.com/questions/699708/variable-order-regex-syntax
  [2]: https://stackoverflow.com/questions/457015/regular-expression-help



Can you provide some examples of why it is hard to parse XML and HTML with a regex?

I have something like this

&gt; aabbabcaabda

for selecting minimal group wrapped by **a** I have this `/a([^a]*)a/` which works just fine

But i have problem with groups wrapped by **aa**, where I&#39;d need something like 
`/aa([^aa]*)aa/` which doesn&#39;t work, and I can&#39;t use the first one like `/aa([^a]*)aa/`, because it would end on first occurence of **a**, which I don&#39;t want.

Generally, is there any way, how to say ***not contains string*** in the same way that
I can say ***not contains character*** with `[^a]`?

Simply said, I need ***aa** followed by any character except sequence **aa** and then ends with **aa***

Regular expression that doesn&#39;t contain certain string

I have an XML file containing one (or more) key/value pairs. For each of these pairs I want to extract the value which is a two-byte hex value.

So the XML contains this snippet:

    &lt;key&gt;LibID&lt;/key&gt;&lt;val&gt;A67A&lt;/val&gt;

Which I can match using the following expression, with the ID in parenthesis.

    Match match = Regex.Match(content, @&quot;&lt;key&gt;LibID&lt;/key&gt;&lt;val&gt;([a-fA-F0-9]{4})&lt;/val&gt;&quot;);
    
    if (match.Success)
    {
      Console.WriteLine(&quot;Found Match for {0}\n&quot;, match.Value);
      Console.WriteLine(&quot;ID was {0}\n&quot;, &quot;Help me SO!&quot;);
    }

How can I change the last part so it returns the ID from the match?

Cheers!


How to extract a substring from a .NET RegEx?

When users create an account on my site I want to make server validation for emails to not accept *every* input.

I will send a confirmation, in a way to do a [handshake validation][1].

I am looking for **something simple, not *the best***, but not too simple that doesn&#39;t validate anything. I don&#39;t know where limitation must be, since any regular expression will not do the correct validation because is not possible to do it with regular expressions.

I&#39;m trying to limit the sintax and visual complexity inherent to regular expressions, because in this case any will be correct.

What regexp can I use to do that?


  [1]: https://stackoverflow.com/questions/156430/regexp-recognition-of-email-address-hard/156441#156441

What is a good regular expression for catching typos in an email address?

When exploring regular expressions (otherwise known as RegEx-es), there are many individuals who seem to see regular expressions as the Holy Grail.  Something that looks so complicated - just must be the answer to any question.  They tend to think that every problem is solvable using regular expressions.

On the other hand, there are also many people who try to avoid regular expressions at all cost.  They try to find a way around regular expressions and accept additional coding just for the sake of it, even if a regular expressions would be a more compact solution.

Why are regular expressions considered so controversial?  Is there widespread misunderstandings about how they work?  Or could it be a broad belief that regular expressions are generally slow?   

Why are regular expressions so controversial?

How can I set a key binding that globally overrides and takes precedence over all other bindings for that key?  I want to override all major/minor mode maps and make sure my binding is always in effect.

This of course doesn&#39;t work:

    (global-set-key &quot;\C-i&quot; &#39;some-function)

It works in `text-mode`, but when I use `lisp-mode`, `C-i` is rebound to `lisp-indent-line`.

I can go through and override this binding in `lisp-mode` and in every other mode individually, but there must be an easier way.  Every time I install a new mode for a new file type, I&#39;d have to go back and check to make sure that all of my key bindings aren&#39;t being overridden by the new mode.

I want to do this because I want to emulate bindings I&#39;ve already learned and ingrained from other editors.

Globally override key binding in Emacs

When I export to PDF via org-mode (C-c C-e d), any words with underscores end up being partially converted to subscript. How can I prevent this from happening?

I found this article on the subject:

[Disabling Underscore subscript in Emacs Tex Mode][1]

However, I either wasn&#39;t able to figure out the correct elisp or it simply didn&#39;t work. Note, I don&#39;t want to change any global font options. I only want this fix to apply to tex/latex/org-mode.

I also found this post, though it didn&#39;t work either:

[disable subscript superscript raise/lower?][2]


  [1]: http://gimbo.org.uk/blog/2007/11/11/disabling_underscore_subscript_emacs_tex_mode/
  [2]: http://groups.google.com/group/gnu.emacs.help/browse_thread/thread/bfc9141338bde20b

Disabling underscore-to-subscript in Emacs Org-Mode export

Sometimes I need to read log files that have ^M (control-M) in the line endings.  I can do a global replace to get rid of them, but then something more is logged to the log file and, of course, they all come back.

Setting unix-style or dos-style end-of-line encoding doesn&#39;t seem to make much difference (but unix-style is my default).  I&#39;m using the undecided-(unix|dos) coding system.

I&#39;m on windows, reading log files created by log4net (although log4net obviously isn&#39;t the only source of this annoyance).

Any hints?





Hiding ^M in emacs

I want to hide the welcome screen.

My `.emacs` file:

     (setq c-basic-offset 4) ; indents 4 chars
     (setq tab-width 4)          ; and 4 char wide for TAB
     (setq indent-tabs-mode nil) ; And force use of spaces
     
     (turn-on-font-lock)       ; same as syntax on in Vim
     
     (setq width (max width (+ (length str) 1)))   ;line numbers
     
     (setq inhibit-splash-screen t)         ; hide welcome screen

I have tried to run the last line of code in my .emacs unsuccessfully.

How can you hide the welcome screen in Emacs?


Unable to hide welcome screen in Emacs

In Emacs Lisp, how do I check if a variable is defined?

How do I do a Find and Replace within a selection in `vi`?

Find and Replace within selection in `vi`

Given a (`char *`) string, I want to find all occurrences of a substring and replace them with an alternate string. I do not see any simple function that achieves this in `&lt;string.h&gt;`.

What function is to replace a substring from a string in C?

Can [this](https://stackoverflow.com/questions/367052/case-preserving-find-replace-in-visual-studio) can be done in Vim?

&gt; What I mean is: searching for &#39;BadJob&#39;
&gt; and replacing with &#39;GoodJob&#39; would do
&gt; the following replacements
&gt; 
&gt;     &#39;badjob&#39; -&gt; &#39;goodjob&#39;  
&gt;     &#39;BadJob&#39; -&gt; &#39;GoodJob&#39;  
&gt;     &#39;badJob&#39; -&gt; &#39;goodJob&#39;  
&gt;     &#39;BADJOB&#39; -&gt; &#39;GOODJOB&#39;



Case preserving substitute in Vim

How do you replace all instances of one string with another in javascript?
Example:

    someString = &#39;the cat looks like a cat&#39;
    anotherString = someString.replace(&#39;cat&#39;, &#39;dog&#39;);

results in anotherString being set to &#39;the **dog** looks like a **cat**&#39;, and I would like it to be &#39;the **dog** looks like a **dog**&#39;

Javascript multiple replace

I have a string. How do I remove all text after a certain character? (*In this case `...`*) &lt;br/&gt;
The text after will **`...`** change so I that&#39;s why I want to remove all characters after a certain one.

Content Type	Original Author	Original Content on Stackoverflow
Question	Dominic Rodger	View Question on Stackoverflow
Solution 1 - Regex	Luke Girvin	View Answer on Stackoverflow
Solution 2 - Regex	ConfexianMJS	View Answer on Stackoverflow
Solution 3 - Regex	xeruf	View Answer on Stackoverflow

Emacs: regular expression replacing to change case

Regex Problem Overview

Regex Solutions

Solution 1 - Regex

Solution 2 - Regex

Solution 3 - Regex

Select columns across different databases

Is PHP thread-safe?

Attributions