How to access attached screen after connection dropped

Here’s the situation, you are using bash’s Screen command because you don’t want your flakey internet connection to affect whatever you are working on, and sure enough, the connection drops. Sometimes, when you try to re-attach to this screen session you are told that the screen session is still attached…

~$ screen -r '1234.somescreensession'
There is a screen on:
1234.somescreensession (Attached)
There is no screen to be resumed matching 1234.somescreensession.

How annoying.

UPDATE:
Here is a simple way to take back that screen session.

screen -D -r '1234.somescreensession'

Kudos to Donncha O’Caoimh

Here is a way a longer way to remove the process that is attached to that screen session, so you can reattach to it and continue with whatever you were doing.

  • figure out which tty is holding on to the screen session by typing into terminal
    ps -ef | grep screen | grep tty
  • result of this should be something like
    testdev 5760 5688 0 12:31 ttyp1 00:00:00 screen -r 1234.somescreensession
  • in this case the tty is 5688, use this to find the login bash that is associated with that tty
    ps -ef | grep bash | grep 5688
  • result of this should be something like
    testdev 5688 5687 0 12:28 ttyp1 00:00:00 -bash
  • kill process
    kill -9 5687

Now you should be free to re-attach to this screen session.

Kudos to David Mackintosh 

Uninstall and Remove Xcode Completely

If you are in a position where you want to remove the colossus that is Xcode, here is the terminal command to use.

sudo /Developer/Library/uninstall-devtools –mode=all

In my case, I was using migration assistant to migrate my applications and user account to a new laptop. My older laptop had an older version of Xcode that I didn’t want included in the migration and as it is so big, I didn’t want to take the chance.

Kudos to Pushkararora.com

HTML5 Data attributes in HTML and jQuery

When writing javascript, it is often necessary to include metadata in the HTML markup, to help define some element or behaviour. There are common options available. You can use hidden inputs and/or standard attributes like class or title to store this metadata. However with HTML5’s data attribute, storing and parsing this data has become a whole lot easier and cleaner.

The syntax is straightforward. Any attribute prefixed with data- will be treated as data storage.

[source language=“html“]<div class="test" data-foo="bar"></div>[/source]

jQuery accesses this data like so…
[source language=“javascript“]var data = $( ‚div.test‘ ).data( ‚foo‘ ); // returns bar[/source]

Support for the data attribute has been added since jQuery version 1.4.3. jQuery’s implementation is smart enough that it can parse the attribute easily and even determine the correct data type used.

What I have found really useful is the fact that the jQuery can parse JSON syntax and return a JSON object. This makes passing data in PHP trivial, using the json_encode method. We also need to use htmlspecialchars method to escape or convert any quotes in the JSON string.
[source language=“php“]
<?php
$test = array( ‚row‘ => 1, ‚col‘ => 6, ‚color‘ => ‚pink‘ ); //create array of data you want to pass to jquery
$test = json_encode( $test ); //convert array to a JSON string
$test = htmlspecialchars( $test, ENT_QUOTES ); //convert any quotes into HTML entities so JSON string behaves as a proper HTML attribute.
?>
<div class="test" data-complex="<?php echo $test ; ?>"></div>[/source]

The jQuery parses the JSON string like so…
[source language=“javascript“]var test = $( ‚div.test‘ ).data( ‚complex‘ ); // returns JSON Object

console.log( test.color ); // outputs pink![/source]

Important to note that this method is also backward compatible with older browsers, so there is no excuse not to give it a go!

Filter IP addresses with PHP

You may at some stage want to filter an online service based on IP address. In other words, you may want to block or grant access to a request based on their IP address. This can be handled in PHP by doing the following.

If you have the IP addresses, then it is trivial.

[source language=“php“]

//First check IP address is valid
$request_ip = $_SERVER[‚REMOTE_ADDR‘];

if ( !preg_match( "/^(([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]).){3}([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$/", $request_ip ) )
return false;

$blacklist = array(
‚111.222.12.11‘,
‚222.111.21.22‘,
‚221.112.11.12‘
);

//check that ip is not blacklisted
if ( in_array( $request_ip, $blacklist ) )
return false;

[/source]

If you want to include a range of IP addresses, best to use a regular expression.

[source language=“php“]

$blacklist_ip_range = array(
‚/^122\.244\.(\d+)\.(\d+)/‘, //for IP address in the range 122.244.0.0 – 122.244.255.255
‚/^123\.(\d+)\.(\d+)\.(\d+)/‘, //for IP address in the range 123.0.0.0 – 123.255.255.255
);

foreach( $blacklist_ip_range as $ip ) {
if( preg_match( $ip, $request_ip ) )
return false;
}

[/source]

If you have a better solution, then please let me know.

Mac mail not sending Gmail email

Infrequently my Mac mail would be rendered incapable of sending email.

It appears the Mac mail client could not connect to the outgoing Gmail SMTP server, smtp.gmail.com, then after a few hours the connection would be restored automatically.

I assumed that my settings must be fine as they remained constant, it must be a problem on the Gmail servers end, but it was happening too often for that to be plausible.

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