Wikipedia:Reference desk/Archives/Computing/2010 October 19

= October 19 =

Windows application icons
What does it mean when Windows, instead of using a program's regular icon, uses that generic looking icon for a program? I can't really describe what I'm thinking of... And the signal to noise ratio on searches for "windows icon" is too high to come up with anything useful.

Let me describe what I saw and maybe it'll help understand what I'm thinking of. I just saw my manager's laptop desktop. On it was the installers for iTunes, RealPlayer, FlashPlayer, two different versions of Firefox (one of them was Firefox 2), and three different versions of Adobe Reader. A utility for setting up a WLAN and another for adding a printer (neither of which he ever has to do on any sort of timely basis). In addition to all that (amongst the 40+ icons on his desktop) were those generic Windows icons.

Would they be shortcut icons for programs that no longer exist and therefore don't have the proper icon? Dismas |(talk) 00:19, 19 October 2010 (UTC)


 * Was it one of these standard Windows icons? If a program file does not contain the icon, or specify the external location for its icon properly, Windows will default to one of its shell icons.  The specific icon used will depend on file type, shell settings, and so on.  Nimur (talk) 00:23, 19 October 2010 (UTC)


 * Yep, it looked like the icon in the first image at location (0,-2), if we're using a standard (x,y) Cartesian coordinate system. I'm figuring that he deleted the programs that they were tied to but didn't get the icon on the desktop.  Dismas |(talk) 00:51, 19 October 2010 (UTC)
 * That would cause the effect you described. It may also have had some other issue loading the proper icon and given up. There are exotic possibilities, but a common one would be that they were links to programs on a network drive that wasn't currently connected. APL (talk) 04:19, 19 October 2010 (UTC)
 * Or a Removable Drive. Or the target has been moved somewhere else or deleted. Sir Stupidity (talk) 11:21, 19 October 2010 (UTC)
 * If you know the program has its own icon, then one of the above seems likely. But it might be a console application that doesn't have one at all; that's the generic "program" icon used for batch files for instance.  --Tardis (talk) 13:46, 20 October 2010 (UTC)

gcc problem
Hi. I'm trying to compile gcc 4.5.1 (needed for emacs) and SVNed that latest revision (165682). Although it configures fine, compiling throws the following error:

/home/rksh/scratch/gcc/host-x86_64-unknown-linux-gnu/gcc/xgcc -B/home/rksh/scratch/gcc/host-x86_64-unknown-linux-gnu/gcc/ -B/usr/local/x86_64-unknown-linux-gnu/bin/ -B/usr/local/x86_64-unknown-linux-gnu/lib/ -isystem /usr/local/x86_64-unknown-linux-gnu/include -isystem /usr/local/x86_64-unknown-linux-gnu/sys-include   -g -O2 -m32 -O2  -g -O2 -DIN_GCC   -W -Wall -Wwrite-strings -Wcast-qual -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition  -isystem ./include  -fPIC -g -DHAVE_GTHR_DEFAULT -DIN_LIBGCC2 -D__GCC_FLOAT_NOT_NEEDED   -I. -I. -I../../../host-x86_64-unknown-linux-gnu/gcc -I../../.././libgcc -I../../.././libgcc/. -I../../.././libgcc/../gcc -I../../.././libgcc/../include -I../../.././libgcc/config/libbid -DENABLE_DECIMAL_BID_FORMAT -DHAVE_CC_TLS -DUSE_TLS -o _muldi3.o -MT _muldi3.o -MD -MP -MF _muldi3.dep -DL_muldi3 -c ../../.././libgcc/../gcc/libgcc2.c \ -fvisibility=hidden -DHIDE_EXPORTS In file included from /usr/include/features.h:371:0, from /usr/include/stdio.h:28, from ../../.././libgcc/../gcc/tsystem.h:87, from ../../.././libgcc/../gcc/libgcc2.c:29: /usr/include/gnu/stubs.h:7:27: fatal error: gnu/stubs-32.h: No such file or directory compilation terminated. make[5]: *** [_muldi3.o] Error 1 make[5]: Leaving directory `/home/rksh/scratch/gcc/x86_64-unknown-linux-gnu/32/libgcc' make[4]: *** [multi-do] Error 1 make[4]: Leaving directory `/home/rksh/scratch/gcc/x86_64-unknown-linux-gnu/libgcc' make[3]: *** [all-multi] Error 2 make[3]: Leaving directory `/home/rksh/scratch/gcc/x86_64-unknown-linux-gnu/libgcc' make[2]: *** [all-stage1-target-libgcc] Error 2 make[2]: Leaving directory `/home/rksh/scratch/gcc' make[1]: *** [stage1-bubble] Error 2 make[1]: Leaving directory `/home/rksh/scratch/gcc' make: *** [all] Error 2 HPS223:~/scratch/gcc%

Googling seemed to reveal that others have had similar problems, but no solution. Does anyone have any ideas? Robinh (talk) 08:30, 19 October 2010 (UTC)
 * (OP here). Thanks to a local guru, I have answered my own question: the trick was to install glibc-devel-32bit, which was unintuitive seeing as my system is a 64 bit SuSe installation.  Thanks anyway, Robinh (talk) 08:43, 19 October 2010 (UTC)

AVG slows down my computer significantly
I've had various versions of AVG Antivirus Free on my Vista laptop since I bought it in late 2007 or early 2008. Yesterday, I downloaded the 2011 edition, and since that time, my computer has been functioning far slower: it's almost as slow as the computer used to be when the full computer scan was running, but I've checked and confirmed that the scan is not running currently, and the slowness continues. Any ideas what I could do to improve performance? I downloaded this program from the AVG website, so I know that it's not some odd sort of virus in disguise. Nyttend (talk) 12:13, 19 October 2010 (UTC)
 * I used to use AVG too and found it slowed the computer an unacceptable amount. I switched to Avira which is a free (for non-commercial use) antivirus program that runs so much faster and uses less memory. I know that's not the best answer to your question considering you obviously want your paid for AVG to work fast, but if you run out of other options give Avira a try. 82.44.55.25 (talk) 14:14, 19 October 2010 (UTC)
 * Thanks for the pointer. I didn't pay for this service; as I said, it's AVG Free, which is also noncommercial.  Nyttend (talk) 19:05, 19 October 2010 (UTC)

wget time-stamping
With the -N option in wget it checks whether the remote file is newer than the local file, and downloads it if it is. However it also checks the size of the file; "If the local file does not exist, or the sizes of the files do not match, Wget will download the remote file no matter what the time-stamps say." I've found with some sites that the size of the remote html files sometimes change (presumably adverts or something) but the page has not been modified in any way, the content is exactly the same, and the last modified headers are the same as they were previously. In these instances wget downloads all the pages again. How can I stop this? I want wget to only check the last modified headers, not the size of the files. I've looked through the wget guide but can't find any way to stop this. 82.44.55.25 (talk) 14:06, 19 October 2010 (UTC)
 * I may be confused but how can the remote HTML file size change but it not be modified in any way? Surely there must be some difference even if only in blank spaces or links to ads or whatever? Nil Einne (talk) 14:37, 19 October 2010 (UTC)
 * In terms of the wider question, I can find several people who've asked but no one has offered any suggestions other then use something else. That and the lack of anything in the documents suggests to me it isn't a currently supported option. Nil Einne (talk) 14:46, 19 October 2010 (UTC)
 * If you care that much about it, why don't you just recompile wget? Surely the part of the check that looks at the file size in addition to date must be like ONE LINE, and you comment it out and it's done.  It'll take you like 2 minutes to find that line, and if you're on Windows and haven't used Linux or C before, like no more than 200 hours to be totally used to your Linux environment and to recompiling everything from source, along with learning enough C to be able to make meaningful source-code changes.  That's the beauty of open-source.  Get to it -- you won't have much of a beard after just 200 hours, and if you wanted to make meaningful kernel-level changes we're talking more like 20,000 hours, but we all had to start somewhere...84.153.229.95 (talk) 15:54, 19 October 2010 (UTC)

cURL is a bit more modern alternative to wget; so consider checking it. I can't see an exact option for what you want, but the cURL documentation is extensive, and I haven't checked it all. cURL also has a programmer's API so you could write custom logic to analyze the HTTP metadata libcurl returns. Or you can call curl from the command line to spit out headers or HTTP metadata and process that with a script. Nimur (talk) 15:40, 19 October 2010 (UTC)

.bif file
Hi! do u know where can I find the bif file on a sd mem card? T.i.a. --217.194.34.103 (talk) 15:58, 19 October 2010 (UTC)
 * Have you checked you can see hidden folders and files? On Windows 7, go to any explorer.exe window, click on organise, then on folders and search options. Under the view tab, change it to 'Show hidden files and folders'. Then check if you can see it.Sir Stupidity (talk) 21:18, 19 October 2010 (UTC)

grep doesn't work on windows7
I just installed grep for windows (version 2.5.4) and typing "grep" on the commandline doesn't do anthing, but if I go into C:\Program Files\GnuWin32\bin> and type "grep" it works. Can you give me EXACT instruction (i'm just a beginner) on how to get it working so if I just type "grep" it works? I'm on windows 7, please don't assume I know anything! I need very detailed instructions, normally when I ask for help I don't know how to do any of the steps anyone tells me to do. Thanks a million!!! Jenny. —Preceding unsigned comment added by 188.174.25.49 (talk) 17:54, 19 October 2010 (UTC)


 * Windows has this concept called the "path". The path is a big list of directories where Windows searches each time you type something from the command line.  You have grep in "C:\Program Files\GnuWin32\bin" but Windows doesn't know to look there when you type "grep" from the command line, so Windows gives up and displays an error.  This link discusses how to add a directory to the Windows 7 path; try to follow those directions to add "C:\Program Files\GnuWin32\bin" to your path, and reply back here if you have any problems.  Make sure you add this directory to the end of the path (don't delete the whole path that you already have).  Comet Tuttle (talk) 17:57, 19 October 2010 (UTC)

Is it possible for a computer virus to evolve?
And to do so on its own without any input from the creator of the virus. ScienceApe (talk) 18:34, 19 October 2010 (UTC)
 * No (at least not given current techniques, and not if you're using the conventional biological definition of evolution). Using computer terminology, biological evolution works on a playoff between expressed and unexpressed code.  i.e., you have a large storage base in the genome of genetic material that doesn't do much or is only rarely executed, and a more restricted set of code that generates the organism and its properties.  as the environment changes, expressed code that is counterproductive tends to kill off that individual organism, while rarely expressed code that is productive becomes more common.  Plus, random mutation is consistently adding new unexpressed code into the genome.  In order for this to be modeled in a computer virus, you'd need (at minimum) some form of code-transference between viruses to produce new distributions of code and to spread both unsuccessful and successful code bits through the population, some non-random method for determining which code bits get expressed and which remain unexpressed in a given virus, some random method for generating new potentially viable code (creating purely random code would not be sufficient), a large enough population of running viruses to make for a statistically adequate population size, and some sort of inbuilt motivational structure (resources to be sought out and consumed, dangers to be avoided, an urge towards code-exchange). Even if you could overcome these programing obstacles, you'd certainly have to construct a special environment for this to happen, because I can't think of a system that could handle the (likely millions or billions) of individual virus threads that you'd need to get something akin to evolution and species diversification.  -- Ludwigs 2  19:03, 19 October 2010 (UTC)


 * What Ludwigs is describing is an evolutionary algorithm. You'd have to program the virus to work in this way, though, so it wouldn't really be without input from the creator. --Mr.98 (talk) 19:12, 19 October 2010 (UTC)
 * How cool. I did not know we had an article on that.  -- Ludwigs 2  21:08, 19 October 2010 (UTC)
 * When a person states that a computer virus "evolved", they mean that someone wrote the original virus. Someone else altered it.  Then, someone altered that.  Then, someone altered that.  Over and over, the virus evolves.  While it does meet your criteria of "without any input from the creator", it is obviously not what you are looking for. --  k a i n a w &trade; 19:07, 19 October 2010 (UTC)
 * You may be interested in Tierra_(computer_simulation). APL (talk) 21:14, 19 October 2010 (UTC)

It would actually be very simple. All you'd have to do is to program the virus to make, with some low probability, a random change to its own code on some occasions when it replicates. It wouldn't work very well unless the code was specially written to be fault-tolerant, because otherwise it would be hard to avoid Muller's ratchet, but in principle it is straightforward. Looie496 (talk) 22:38, 19 October 2010 (UTC)

Code displayed on a web page
I was browsing the net and came across this site www.stalltheball.ie and the following code is displayed on the home page

Warning: session_start [function.session-start]: Cannot send session cookie - headers already sent by (output started at /home/stall/public_html/includes/application_top.php:41) in /home/stall/public_html/includes/functions/sessions.php on line 102

the code is only visible when I view the page using Opera, I tried IE and Firefox and the error doesn't appear. So is it an error on the site or is it the Opera browser? Mo ainm ~Talk  19:14, 19 October 2010 (UTC)


 * The site. Strictly it's not showing you source code, it's showing you an internal error message (intended for developer consumption, not for users). For any production site, it's very bad form indeed to show a regular visitor an internal error message like this.  The fact that it doesn't work with a given browser just means they haven't tested it properly. -- Finlay McWalter ☻ Talk 19:21, 19 October 2010 (UTC)
 * So any idea what is causing it to display is it that session_start is not being called at the correct time in their source code? Mo ainm  ~Talk  19:38, 19 October 2010 (UTC)


 * No, you'd have to see the source for their web app to see what they're really doing wrong - error messages are the computer equivalent of "my leg hurts", and are rarely enough to really figure out what's wrong, without a proper examination. Incidentally the site works fine for me in Opera 10.61 (build 10.61) on Linux. -- Finlay McWalter ☻ Talk 19:55, 19 October 2010 (UTC)
 * Thats great thanks for the info, also the error message is not being displayed anymore for me either. Mo ainm  ~Talk  20:04, 19 October 2010 (UTC)

Samsung mobile/pc cable
What cable do I need to sync a Samsung GT-E2121B to a PC? Thanks, DuncanHill (talk) 19:23, 19 October 2010 (UTC)


 * Samsung's support page for this phone is here, but I don't see any mention of such a cable in the (not very detailed manual). I do see the phone has BlueTooth, so you should be able to sync it over that. A little usb BlueTooth adapter should cost very much (and may be more cost effective than a cable). -- Finlay McWalter ☻ Talk 19:34, 19 October 2010 (UTC)
 * You meant shouldn't right? Nil Einne (talk) 19:46, 19 October 2010 (UTC)
 * Oops, yes. In the UK that means £10 or so. -- Finlay McWalter ☻ Talk 19:51, 19 October 2010 (UTC)


 * Thanks, I'll see about getting one of those then. I did email Samsung to ask them, but they said to ask retailers, but the retailers they suggested were places like Argos or Curry's, who wouldn't have a clue. DuncanHill (talk) 21:13, 19 October 2010 (UTC)


 * Before you do that, download and install the Samsung app that you'll be using to sync. Verify that it does have a connect-with-bluetooth option; I'd be very surprised (and disappointed) if it doesn't - the Nokia equivalent certainly does.  The nice thing about having a bluetooth adapter is that it should work with any future phone you buy (rather than having to get a new cable for a new phone), it should work with friends' phones (so you could use it to get photos etc. off a visiting friend's phone), and you can use bluetooth accessories with the phone (for example, I used my little Nokia bluetooth headset with Skype on the PC). -- Finlay McWalter ☻ Talk 21:27, 19 October 2010 (UTC)
 * Thanks, yes the software does have a bluetooth option. DuncanHill (talk) 10:44, 21 October 2010 (UTC)


 * You should BTW be able to get a cheap Bluetooth device for under US$3 shipped from China/HK from a place like Buyincoins, DealExtreme , Lightake , Kaidomain  or eBay. Can't comment on any customs problems although my memory is they don't care in the UK if it's under £10 or something and I don't think they'll care even though it's RF so could theoretically violate UK law on transmission power or frequencies or whater. Shipping will take a while of course (I normally get stuff in 1-2 weeks to NZ but I think UK can be longer and more importantly it's starting to get near busy season, I'm already reading of people complaining about long shipping times and I actually think I'm encountering it too). Nil Einne (talk) 10:17, 20 October 2010 (UTC)