Wikipedia:Reference desk/Archives/Computing/2010 April 21

= April 21 =

how does apple keep flash from running?
does anybody know this? (i'm just curious, not interested in any hacking). does the OS recognize the flash app code and refuse to load it? or does it recognize the flash files and refuse to load them? or what? frankly, the concept of an OS that refuses to run a particular application (rather than not having the resources) is new to me. Gzuckier (talk) 03:26, 21 April 2010 (UTC)


 * I assume you're referring to the iPhone and the iPad since Flash does run on Apple's Mac OS X. Most of the time, the Flash Player is pre-installed on smart phones. But Apple refuses to pre-install it. The next possible way to install the Flash Player is through the iPhone App Store. But Apple won't allow it in its App Store. So, the only remaining way to obtain the Flash Player would be to jailbreak your iPhone and download it through a third-party store (like Cydia). You can't install apps on the iPhone from anywhere but the App Store unless you jailbreak your phone. But I don't know if Adobe will ever bother to release a final version of an iPhone flash player since most iPhone users won't be able to install it. Last time I heard, it was in beta.--Best Dog Ever (talk) 03:48, 21 April 2010 (UTC)


 * You are making a HUGE assumption that there is a flash player that will run just fine on an iphone and that the iphone OS refuses to install it. Instead, ask if there is a flash player that will run just fine on the iphone OS.  When programs do not exist, nobody is refusing to install or run them.  You may as well ask why your computer refuses to run Duke Nukem Forever. --  k a i n a w &trade; 04:43, 21 April 2010 (UTC)


 * Yes, it's a strange assumption that Flash should just work, as if by magic. If you have a brand-new Windows install, Flash isn't going to work on that, either.  Your web browser will say something like "Plugin Required" and send you to download and install Adobe Flash Player.  The difference is that on the iPhone, there is no Adobe Flash Player to download and install.  -- Coneslayer (talk) 12:13, 21 April 2010 (UTC)


 * That's odd. Why won't Apple "allow it in its App Store"?  Seems like a strange thing for Apple to say.  Astronaut (talk) 12:54, 21 April 2010 (UTC)


 * Apple fiercely defends its walled garden, and Apple hates Adobe. Here's a longer discussion.  -- Coneslayer (talk) 13:30, 21 April 2010 (UTC)


 * Apple's explanations for not having Flash on the iPhone state that it doesn't run well enough, it's a security risk, and flash is an interpreter so it wouldn't be allowed on the App Store even if the first two points aren't true. Caltsar (talk) 14:46, 21 April 2010 (UTC)


 * This recent asktog column says, "Jobs doesn’t like Flash. It has a slow, clumsy, weird interface, and he’s elected to "cripple" his mobile devices to rid the industry of its dependence on it." Tog goes on to compare this decision to Jobs's insistence that the original Macintosh not have arrow keys on its keyboard, temporarily "crippling" the Macintosh in order to specifically make sure that Mac software developers designed their apps around the use of the mouse, rather than directly porting their existing IBM PC apps, which relied on the arrow keys for things like menu navigation.  Comet Tuttle (talk) 17:45, 21 April 2010 (UTC)


 * A Potential misconception here is that flash files "just work" on any computer and would need to be "blocked". They don't. They need a plug-in written for every type of computer they run on.   Adobe works hard to make it seem like it "just works", but actually it depends on a getting a piece of software from Adobe that's separate from your web-browser.
 * It's not a matter of blocking them as much as it is never giving you the software they depend on in the first place. APL (talk) 15:10, 21 April 2010 (UTC)


 * Except in this case, it is deliberate blocking. Adobe would love to produce a version of Flash for the iPhone and iPad and would take the time to figure out how to make it happen, except they know Apple won't approve it, and so it would be a waste of effort. If Apple said they'd approve Flash in some form (e.g. Flash Lite), you can bet that Adobe would find a way to bundle it up. Apple has made a deliberate choice to ban Flash tech from their mobile products; it is not Adobe's fault to any particular degree. (Apple of course justifies it as a technical decision, but won't define the technical objections. If they said, "it could only use x% of the processor time", I am sure Adobe would modify it as requested. As it is, they've basically just been told, "no." Personally I find this a bit ridiculous—worse than anything Microsoft ever did—and am pretty appalled by it, even as someone who uses a MacBook as his main computer.) --Mr.98 (talk) 17:50, 21 April 2010 (UTC)


 * APL's point is that in order for Flash to work on any device, Adobe first has to write a version of their Flash player for that device, and it's not as simple as Apple saying "yes" and flipping a switch and then Flash works on the iPhone. Comet Tuttle (talk) 17:54, 21 April 2010 (UTC)


 * Right, but the issue here is not a technical one. If Apple did "flip the switch"—allow Adobe to code a Flash application for the iPhone—there would be one probably near instantly. Adobe is jumping at the bit for this. The problem is not that Adobe has not or could not write an application for the iPhone. The problem is 100% Apple not letting them publish a version for it. It is not a technical issue. It is business. --Mr.98 (talk) 18:13, 21 April 2010 (UTC)


 * Well, we understand that Apple is deliberately blocking Flash on the iPhone, by barring any apps that carry a Flash player; but saying "the issue here is not a technical one" is, I think, misleading to the original poster, whose question shows that he or she is under a misapprehension about how Flash has to be written specifically for each platform. I think a more complete answer would be "For Flash to run on the iPhone, Adobe has to take the technical effort to write a Flash player for the iPhone.  That has happened, and the Flash player on the iPhone is ready; but Apple has made the business decision to ban any app that carries a Flash player."  Comet Tuttle (talk) 18:27, 21 April 2010 (UTC)
 * No, I understand that flash would have to be ported to the Ipad/phone platform, but assumed that it's a matter of reworking the big pile of C or whatever, as with porting anything to anything. Hadn't occurred to me that it would have to be offered via the Apple store, etc.... so does that mean that if I were a genius, I could write a Flash interpreter via the Ipad SDK or whatever for my own use that would work? Not that I could, but hypothetically? Gzuckier (talk) 00:52, 22 April 2010 (UTC)


 * You wouldn't have to write one from scratch. You could just port Gnash to the iPhone using Xcode. Here's the source code for Gnash: .--Best Dog Ever (talk) 01:16, 22 April 2010 (UTC)


 * A week after the original poster asked this question, Steve Jobs wrote a letter / blog post detailing why Apple isn't allowing Flash on the iPhone or iPad. Comet Tuttle (talk) 17:15, 29 April 2010 (UTC)

Googlebot indexing
Will a subdirectory-tree on a web server, that has has permissions 777, and which is used for uploads and as a file repository for a php-based application, located on a site which itself is indexed by googlebot, also be visible to googlebot and similar web crawlers?

The application in question is MediaWiki. Short urls (without the question mark) are not used. There are no ingoing links to the directory, its name appears only in LocalSettings.php. There is no anonymous ftp, and login is required to access the wiki. I'm also assuming that the directory has a long, randomly generated name.

I've asked a question similar to this one before, read Web_Crawler, as well as this xkcd comic, but am still not totally sure about the answer. Thanks, --NorwegianBluetalk 07:43, 21 April 2010 (UTC)
 * Put an XML site map on the site so the crawler will know where to find stuff. That works better than relying on the link graph. 66.127.53.162 (talk) 08:17, 21 April 2010 (UTC)
 * Sorry for not being clear enough, the intention is that the crawler should not be able to index these files. --NorwegianBluetalk 10:46, 21 April 2010 (UTC)
 * Had you considered using a robots.txt exclusion file? --Phil Holmes (talk) 15:08, 21 April 2010 (UTC)
 * Oh. Yes, use either a robots.txt or comparable meta tags (see the article Phil Holmes linked to).  Note that there are evil crawlers that ignore such directives.   66.127.53.162 (talk) 16:31, 21 April 2010 (UTC)


 * If you want to prevent a web spider from indexing it, the best option is to restrict access to that directory, either by requiring a login or by denying delivery at the server level (for example, deny all except an IP whitelist; or require a login/password; and control this with an .htaccess file). Alternately, if you have absolutely no links to that subdirectory, ("security through obscurity"), the directory's presence should be totally unknown to all spiders.  Note that if you ever accidentally create a link (or if a spider somehow guesses the directory name), the "obscurity" scheme provides no measure to deny access to that robot.  (I know that in MediaWiki, especially if you post files on the wiki, there will be links to that upload directory - but you stated that these wiki pages already have some access control).
 * Ideally, you want identical access control for the .htaccess file and the wiki login - there may be some way to do this using session-sharing and a unified login. Ultimately it boils down to how strongly you seek to protect / deny access.  I strongly recommend that you use an authentication scheme - htaccess files are easy to understand and implement, and are a good way to augment a "security through obscurity" scheme.  If you are particularly worried about protecting your content, consider requiring additional measures, (in order of increasing complexity/security): secure HTTP, requiring a captcha, encrypting the directory contents, or replacing the simplistic "uploads" directory with a full-blown web-application and secure network-storage scheme that enables per-user authentication.  Eventually, your secure system must migrate to a non-public network if you want the maximum level of security.  Nimur (talk) 17:47, 21 April 2010 (UTC)
 * If you're trying to run a private site then you have to use login authentication and trust your users, yes. Keep in mind that if the site has any external links at all, those can disclose the site's existence through referer headers when users click on the links.  If you're just trying to keep a low profile from mass visibility (spelled Google), then robots.txt seems sufficient for most purposes.  66.127.53.162 (talk) 20:22, 21 April 2010 (UTC)

Although "robots.txt" is a perfectly valid answer to my question, it makes sense to consider not-so-friendly bots or other intruders, who might use "robots.txt" for the exact opposite of what it's intended for. This is indeed a case of "security through obscurity". So it seems .htaccess + .htpasswd is the way to go. I wasn't aware it protected all subdirectories (of which there are a lot in a MediaWiki file repository). I tried it, and my testing so far indicates that its presence doesn't confuse the MediaWiki software, files are uploaded and downloaded fine. However if I try to browse the "secret" directory, which used to be accessible to someone who knew its name, I'm now prompted for a username and password. Thanks everyone! --NorwegianBluetalk 16:55, 22 April 2010 (UTC)

Editing MS Word dictionary
While proof reading a document I add erroneous entries into the dictionary because I click on the wrong item in the right click menu. while I should have clicked on the right substitution I wrongly click on the add to "dictionary". How can I delete these custom entries?--117.204.83.62 (talk) 09:45, 21 April 2010 (UTC)
 * In Word 2003:
 * open a document, ensure there's some mis-spelled text in the document
 * F7 (brings up the spell checker dialogue box)
 * Options
 * Custom Dictionaries
 * Select CUSTOMDIC and Modify
 * Add to or delete items from the CUSTOMDIC --Tagishsimon (talk) 09:54, 21 April 2010 (UTC)
 * Thank you for the help.--117.207.146.213 (talk) 10:02, 21 April 2010 (UTC)

Win XP language and keyboard
I changed my language on XP from US English to English UK but the UK English keyboard doesn't suit me because I get @ symbol when I press " key. So I kept the language as UK English and chose the keyboard as US English. However, when I press " nothing appears. It the symbol is to appear I have to press the space bar once. No space is added though. How can I get around this? --117.207.146.213 (talk) 10:05, 21 April 2010 (UTC)


 * What is the physical layout of your actual keyboard? US keyboards and UK keyboards have different layouts and in particular Shift-2 will create a '@' on a US keyboard and a '"' on a UK keyboard.  However, the dead key behavoir you describe seems to be a feature of the US-International keyboard, the UK-extended keyboard layouts and other layouts too.  Maybe you picked the wrong version in the XP keyboard settings or you have a different keyboard altogether.  Astronaut (talk) 12:49, 21 April 2010 (UTC)
 * The physical layout of my keyboard is US keyboards as I guess from the image there. I have chosen the US-International keyboard along with English UK. I see that it has this dead key behaviour. Let me try US keyboards and see.

-117.204.89.229 (talk) 07:04, 22 April 2010 (UTC)
 * I removed US International Keyboard and added US keyboard. That fixed it. Thank you for the advice. -117.204.91.238 (talk) 12:28, 22 April 2010 (UTC)

Is there a way to determine the default gateway in JavaScript, similar to myIpAddress for the IP?
I am trying to create a proxy autoconfiguration file (PAC), however, I am running into a Firefox bug: myIpAddress returns an IPv6 address under Windows 7, even though the IPv6 addresses aren't used (they are Link-local only). As Firefox doesn't support myIpAddressEx (which returns a list of all IP addresses the client has, IPv4 and IPv6 alike) like Internet Explorer does, I'm stuck here, as I need to switch proxies depending on the network the client belongs to.

However, since I don't need the IP, only the network, and only the IPv4 network has a defined gateway address, I am hoping that there is a way to find out the default gateway in JavaScript, so I could use that for my script. Any ideas? -- 78.43.60.58 (talk) 17:54, 21 April 2010 (UTC) Addendum: I found this snippet of code that returns 127.0.0.1: alert('Your IP address is: '+java.net.InetAddress.getLocalHost.getHostAddress); It seems that it calls Java from within JavaScript, which makes me wonder if If Java is not affected by the IPv6 bug I'm seeing in JavaScript, this might help me.
 * this will work from a PAC file and
 * there's a command to query the other IP addresses or the default gateway instead of getLocalHost

Anyone out there that knows enough Java to change that one-liner into something that returns the non-localhost IP(s) or the default gateway? -- 78.43.60.58 (talk) 18:32, 21 April 2010 (UTC)

torrent proxy
If I use a proxy server with utorrent, and select "Use proxy server for peer-to-peer cnnections", will my real ip be compleatly hidden from others, or is there some way it could leak? —Preceding unsigned comment added by 81.198.37.158 (talk) 18:11, 21 April 2010 (UTC)
 * It can always leak. 66.127.53.162 (talk) 20:24, 21 April 2010 (UTC)

What happened to Yahoo mail?
I found out (probably here) that you can click on the yellow triangle twice if there is one. This is what came up and it gave me the option to copy, so I did. ---

Webpage error details

User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; WOW64; Trident/4.0; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.5.30729; .NET CLR 3.0.30729) Timestamp: Wed, 21 Apr 2010 20:47:21 UTC

Message: Exception thrown and not caught Line: 1 Char: 45847 Code: 0 URI: http://mail.yimg.com/d/combo?/mg/10_1_9/js/yui_utils.js&/mg/10_1_9/js/core.js&bc/bc_2.0.4.js&/mg/10_1_9/js/darla.js&/uh/15/js/uh_mail_rsa-1.0.3.js&/mg/10_1_9/js/async.js&/ult/ylc_1.9.js&/mg/10_1_9/js/imboot.js&/gx/t7a/js/yui_loader_mg/34541ce650d3379b3d52c78d4fe681a9_1.js&/gx/t7a/js/combo/init/us/0f36956c5c2ed4808b5a7a2be027ffad_1.js&/gx/t7a/js/combo/init/us/ycw_gx_1.js --- I usually notice the time the draft was last saved has changed when I've updated an email I am composing (I use this as a notepad), but I happened to see this one hadn't changed in two hours. I looked and there was the yellow triangle. I clicked on "Send" but still have a rotating circle beside the arrow. So I copied and pasted to a new email and it sent fine.

Here are the details of my computer, at least on the date at the end of those details. Vchimpanzee ·  talk  ·  contributions  · 21:12, 21 April 2010 (UTC)

By the way, what do you call that yellow triangle on Wikipedia? When I click on a link, I get Nazi concentration camp badges. Vchimpanzee ·  talk  ·  contributions  · 21:14, 21 April 2010 (UTC)


 * I just logged into my Yahoo Mail account, and I don't see a yellow triangle when viewing my Inbox, or when composing a new e-mail message. Could you explain what screen you're on, and where the yellow triangle is at?  Could you provide a screenshot?  Comet Tuttle (talk) 22:13, 21 April 2010 (UTC)


 * It's quite common for web pages to produce errors that can be revealed by clicking the yellow triangle. Firefox does this a different way, and you can see errors with Tools, Error Console.  Both hide errors because they are so common and can generally be ignored, and I would recommend doing this.  In the case of your page that you say "hadn't changed in two hours" it's possible that the session for the page had timed out and caused the error.  --Phil Holmes (talk) 08:29, 22 April 2010 (UTC)
 * Nope, that never happens. Vchimpanzee ·  talk  ·  contributions  · 15:32, 22 April 2010 (UTC)

Create CD-Audio from DVD soundtrack
Hi, I have a Panasonic DVD recorder (DMR-EX75) which has a built-in Freeview tuner, so I can record both TV and radio programmes to the HDD, and then burn those that I want to keep to a DVD-R/RW, DVD+R/RW, or DVD-RAM. Depending on the disc type used, the programmes are recorded in either DVD-Video (IFO/BUP/VOB files) or DVD-VR (IFO/BUP/VRO files) format. If I have recorded a radio programme, the recording has a video component which is a piece of still text giving basic information like the channel it was recorded from. The only bit I'm interested in is the audio; but the Panasonic machine won't burn to a CD-R or CD-RW.

What I want to do is take the IFO/BUP/VOB files of the DVD-Video format from the DVD, strip the video information to leave only the audio, and burn to a CD-R or CD-RW, so that it can be played back in a regular CD player. My PC has a CD burner which will read any of the above disc types, but RealPlayer will only recognise those in DVD-Video format - it doesn't like those in DVD-VR format (recorded to a DVD-RAM). What software should I use on my PC to convert a DVD soundtrack into a playable audio CD? -- Red rose64 (talk) 21:49, 21 April 2010 (UTC)


 * Typing "rip audio dvd" into Google (without the quotation marks) gives a large number of suggested solutions. I'd suggest investigating some of those and letting us know if you need further help.  --Phil Holmes (talk) 08:25, 22 April 2010 (UTC)