Wikipedia:Reference desk/Archives/Computing/2007 March 21

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[edit] March 21

[edit] Alias with command line argument in OS X?

Hi. Could someone tell me how to make an alias to a program with a command line argument in OS X Tiger? Thanks!--Ryan 00:52, 21 March 2007 (UTC)

I don't use OSX, but it is Unix-like, so I expect it to have "ln -s filename symbolic_link". --Kainaw (talk) 01:13, 21 March 2007 (UTC)
ok, the ln comand exists, now could you give me the exact syntax? THanks.--Ryan 01:37, 21 March 2007 (UTC)
Exactly as I noted: ln -s filename symbolic_link where "filename" is the filename you want to link to and "symbolic_link" is the symbolic link name you want to use. For example, you have a file /home/jojo/homework8.txt and you want to use /usr/local/pub/homeworks/jojo8.txt, you would type ln -s /home/jojo/homework8.txt /usr/local/pub/homeworks/jojo8.txt. Then, when you access jojo8.txt, the computer links right to homework8.txt. --Kainaw (talk) 02:12, 21 March 2007 (UTC)
You might be more interested in the alias builtin to most *nix shells. If memory serves, OS X Tiger uses bash by default (otherwise you'll probably be using tcsh). In general, to create an alias you would type something like "alias aliasname='program_name with arguments'" (sans double quotes) at the shell prompt. Example:
   $ alias ll='ls -l'
   $ ll
   total 20
   drwxrwxr-x 2 mattb mattb 4096 Aug 17  2006 manuals
   -rwxr-xr-x 1 mattb mattb 8323 Sep 22  2005 manuals.htm
   drwxr-xr-x 2 mattb mattb 4096 Sep 26  2005 pdf
Note that aliases are only in effect for the current command shell session. If you want to keep them around for future sessions you'll want to include them as a line in one of your shell's startup script (~/.bashrc for bash). -- mattb @ 2007-03-21T04:41Z
Of course. That is what he wants. I put my alias commands in my .bash_rc file so they are always there. I read the question wrong. I read "how to make an alias filename for a program by using some function on the command line." --Kainaw (talk) 13:15, 21 March 2007 (UTC)
Well, the question is unclear, since "alias" can mean so many different things. Also, note that there's no underscore in .bashrc . --TotoBaggins 13:18, 21 March 2007 (UTC)
He did say "alias to a program with a command line argument" in his original question. The "command line argument" part is pretty indicative. -- mattb @ 2007-03-21T17:52Z
There's also Alias (Mac OS), which I thought s/he meant, as in "make an icon that will invoke program foo as foo --some-argument". --TotoBaggins 22:51, 21 March 2007 (UTC)

[edit] Blu-ray and HD DVD Focal Length

I was wondering if anyone knows what these are.J.delanoy 01:15, 21 March 2007 (UTC)

Don't know if this is helpful but the article on Wikipedia says that the wavelength for Blu-ray is 405nm. Is that the same thing as focal length?Mix Lord 02:07, 21 March 2007 (UTC)

No, wavelength is not the same as focal length. The focal length is probably comparable to that of other optical disks, a few millimeters. If you require an actual figure, you can always buy a copy of the specifications books. [1] -- mattb @ 2007-03-21T02:25Z
it doesn't really matter, I just wondered if it was closer to the surface than a DVD. Thanks for the answers!!!!J.delanoy 14:43, 21 March 2007 (UTC)
I doubt it --frotht 16:06, 21 March 2007 (UTC)

My badMix Lord 00:43, 22 March 2007 (UTC)

A little Googling found that Blu-Ray recoding surface is 0.1mm from the surface. HD-DVD is 0.6mm from the surface. --24.249.108.133 14:45, 27 March 2007 (UTC)
OK, Thanks for the help!!!!J.delanoy 16:02, 27 March 2007 (UTC)

[edit] Wireless Sensor Network

can you please explain the meaning of this expression p=h(x©t)


where p is priority h is a hash function and t is time and x is a node indentifier


—The preceding unsigned comment was added by 84.255.156.97 (talk) 08:49, 21 March 2007 (UTC).

The copyright symbol © is not a mathematical function. That is what I see between the x and t in your question. Whatever symbol you intend to use is apparently not in my font set. So, you'll need to explain the function more in order to have the meaning explained in return. --Kainaw (talk) 16:21, 21 March 2007 (UTC)

[edit] DVD converting

Hi I just bought Madonna's Confessions Tour DVD and i thoguht it was awesome. Is there any way I can put it in my iPod for free? Thanks —The preceding unsigned comment was added by 219.78.194.72 (talk) 11:46, 21 March 2007 (UTC).

You can rip it to your hard drive using DVD Decrypter, then convert it to iPod format using Videora iPod Converter.

[edit] Doing a left join among three tables.

I have three tables; I want to left-join the latter two to the first one. Here's an example of what I'm talking about.

Table A:

Name Price ID
Apple 1.00 1
Orange 2.00 2
Pear 1.50 3
Kumquat 3.00 4
Table B:
Brand ID
Smith 1
Jones 2
Table C:
Type ID
Citrus 2
Green 3

I want to create a query which will return this:

Name Price Brand Type ID
Apple 1.00 Smith NULL 1
Orange 2.00 Jones Citrus 2
Pear 1.50 NULL Green 3
Kumquat 3.00 NULL NULL 4

I'm looking for a way to do a left join between three tables instead of just two. I'm using PostgreSQL, if that helps. grendel|khan 14:36, 21 March 2007 (UTC)

Aha! Answered my own question. Apparently you can stack left joins, at least in PostgreSQL: SELECT * FROM a LEFT JOIN b ON (a.id=b.id) LEFT JOIN c ON (a.id=c.id) returns exactly what I wrote above. grendel|khan 15:06, 21 March 2007 (UTC)
You can stack joins of all types - even mixing and matching them - in every SQL database system I've used. --Kainaw (talk) 16:18, 21 March 2007 (UTC)

[edit] PC problem that impacts wikipedia

Over the past year or so, when I type the word c-h-a-t it is replaced with MFEM. I have no idea how this is occurring, but it sometimes leads to sweeping changes within wikipedia. Does anyone know how to solve it? Personal research has given me nothing to solve the problem so far. Thegreatdr 15:13, 21 March 2007 (UTC)

Possibilities:
  1. Whatever editor you're using has a "spelling correction" for the word "c-h-a-t".
  2. You have a keyboard "macros" program (like QuickKeys) that someone trained to respond to the word "c-h-a-t".
Atlant 16:13, 21 March 2007 (UTC)


[edit] digitizing audio tapes

I work for a museum that wants to digitize a bunch of audio cassette tapes, and I'm trying to figure out whether it's worth it to contract it out to professionals. I know that once the tapes are digitized, there's all kinds of fancy software out there to clean up the sound. But what about the digitization itself? Is there some process that professionals use that's substantially better than just plugging a decent tape player into a computer with a decent sound card? Thanks! --Allen 15:52, 21 March 2007 (UTC)

I would think you're pretty much paying for that fancy software and very high quality tape heads --frotht 16:08, 21 March 2007 (UTC)

Any time I've been involved in a "simple" one-off project like this, I've regretted it. The hundred and one "unknown unknowns" that will plague you have already been solved by the professionals in their first year in business. I'd say contract it out if it's a big job and you can afford it. --TotoBaggins 16:11, 21 March 2007 (UTC)

If you do decide to try this yourself, you might consider trying either Roxio Toast or BIAS's Soap. Either automate a fair amount of the drugery.
Atlant 16:18, 21 March 2007 (UTC)
Thanks for the responses! --Allen 12:50, 22 March 2007 (UTC)

Whatever you decide, do a test first and determine if the quality is acceptable. If you are considering multiple options, test the same audio by each method you are considering, then compare the results. StuRat 18:25, 22 March 2007 (UTC)

[edit] Ubuntu/firefox default web font

What is the default web font in Ubuntu (with firefox)? For example here I see Times New Roman in Windows, but something different in Ubuntu. →Ollie (talk • contribs) 16:45, 21 March 2007 (UTC)

  • Just open Preferences/Content, and it'll list it there. I think its Helvetica? —Dark•Shikari[T] 17:44, 21 March 2007 (UTC)
Unfortunately the option is blank, and the advanced dialogue box just gives the generic "serif". →Ollie (talk • contribs) 18:29, 21 March 2007 (UTC)
Probably Bitstream Vera or DejaVu. -- Consumed Crustacean (talk) 22:14, 21 March 2007 (UTC)
Thanks for this, Bitstream Vera Serif looks closest to me. →Ollie (talk • contribs) 18:33, 22 March 2007 (UTC)

[edit] Peter Answers

How does http://www.peteranswers.com work? My friend did it, and it worked, but it doesn't work when I do it. —The preceding unsigned comment was added by Whazzit (talk • contribs) 17:14, 21 March 2007 (UTC).

  • Its really easy.It is a big prank. People fool their relatives and friends by showing them this.this is how it works. Type a period in the first box instead of the P. You will notice that regardless of what you type next, it will look as if you're typing the petition. Instead of the petition, type the answer to the question. Then type the question in the second box.cool huh? nice way to trick people —Dark•Shikari[T] 17:45, 21 March 2007 (UTC)
Wasn't there just a reference desk question on this? read -- mattb @ 2007-03-21T17:47Z

[edit] games on a pin drive, then play on your laptop

I saw this kid playing super smash bros (n64 version) on his laptop using his pin drive. How can i get this great game on a pin drive? —The preceding unsigned comment was added by 68.157.18.147 (talk) 19:50, 21 March 2007 (UTC).

You must use an n64 Emulator, and obtain a copy of the game usually called a Rom. Note that the legality of doing this is dubious. It doesn't matter what kind of drive you use. -- Diletante 21:15, 21 March 2007 (UTC)
And please note that I believe you mean pen drive :). JoshHolloway 21:37, 21 March 2007 (UTC)
Either that, or they went and came out with a new technology without telling me. (Although a terabyte of memory on the head of a pin would be cool, the connector size would then become an issue.) StuRat 18:20, 22 March 2007 (UTC)
Also note that the legality isn't dubious, it's downright illegal --frotht 01:30, 22 March 2007 (UTC)
Well this is not legal advice, but if you dumped the rom yourself from a cartridge that you owned you are probably well within your rights to play that rom on an emulator. -- Diletante 02:09, 22 March 2007 (UTC)

oh ok, cuz all the kids at this computer school do it so i was just wondering how. So i guess 500 students are breaking the law everyday. Ok thanks anyway.

[edit] Game loading times and intro FMV.

So I just got the stalker game and, wow, it's amazing, I'm really enjoying it. So I start a new game and it's got a bit of a load time, and I'm sitting there waiting for it to load, and as soon as it loads it goes straight into a FMV. That's fair enough, every game I've ever come across does that. But in this day and age of multi tasking, why can't a computer still LOAD a level WHILE playing the FMV? Most games have a little animation going while loading, so why can't they just play the FMV? FMVs have been around since x486 days, they aren't processor intensive, so why hasn't a single game I've ever seen, even on consoles, load a level and play a FMV? Ok, the two disk tasks would slow down the loading, but still, with SATA and raid and stuff why can't any computer seem to be capable of what seems not such a big deal? Vespine 22:58, 21 March 2007 (UTC)

As I see it, the programmer has 4 choices:
  • Load data, and then stream the video - this i what you describe.
  • Load video, then load the data in the background - possible, but would take longer if you didn't want to watch the video.
  • Load both at the same time - as the data is on different parts of the disk, the laser would need to skip between them (non-sequential reads). This is really quite slow. Plus, CD-ROMs and hard drives are optimised to read everything in sequence.
  • Interleave data and video - there's no guarantee your PC could handle that rate of video and data loading, so it would need to buffer quite a bit or risk the video skipping. Plus, again, if you want to skip the video it will take longer, as it would still need to load (or skip) through the video data. And it would be harder to develop.
Out of the 4, loading data and then video is the lesser of 4 evils (assuming the video is skippable). --h2g2bob 00:14, 22 March 2007 (UTC)
I don't know, if the FMV was say 30 seconds and 5MB, surely that could load up in a snap and play in the back ground while the level loads, in fact, I'm going to go run a mpg on my media player and load the same game tonight and see how much longer it takes I'm sure it will work, if two applications can do it, why can't they code one application to run two threads or whatever it is that it requires?Vespine 00:57, 22 March 2007 (UTC)
playing video may not be very processor/memory intensive, but any interruptions caused by other operations will be highly noticeable and annoying, so they probably chose to annoy the user with loading rather than risk the more annoying video-skipping -- Diletante 00:42, 22 March 2007 (UTC)
I don't think there's any reason it shouldn't be possible. You only need to buffer a few seconds ahead- and don't be unrealistic, nonsequential reads aren't that bad at all. It would be pretty much a matter of loading the level and every few seconds returning to the FMV for a few million cycles to update the buffer. This is entirely feasible. --frotht 01:28, 22 March 2007 (UTC)

[edit] Computer games with LOTS of statistics

I'm looking for a game with lots of detail and statistics that focus around character development or empire building. Some examples:

  • Championship Manager series (lots and lots of stats)
  • Most roguelikes (Nethack, Angband, Dwarf Fortress)
  • Ascendancy

The focus here is STATS, mainly. If you can suggest any obscure or little-known games I'd prefer it but please run by some obvious ones if you think they are good candidates, especially if they are similar to Championship Manager in scale. —The preceding unsigned comment was added by Magic Window (talk • contribs) 23:46, 21 March 2007 (UTC).

I am not familiar with the games you listed (except roguelikes) but you might be interested in Empire Classic (computer game) I know that there are still active games of wolfpack empire running these days so check out the link at the bottom of the article. I've only played it a tiny bit years back but I know it is full of numbers and statisttics. -- Diletante 00:02, 22 March 2007 (UTC)
Ascendancy is one of my favorite old-school games. Maybe you'd be interested in Tactical RPGs in general (Final Fantasy Tactics/Tactics Advance). I also really liked the MechCommander game. --Wirbelwindヴィルヴェルヴィント (talk) 04:52, 22 March 2007 (UTC)
If I recall correctly, Sid Meier's Civilization franchise has quite a bit of micromanagement. − Twas Now ( talk • contribs • e-mail ) 08:45, 22 March 2007 (UTC)
My mind immediately went to Space Bucks, a 1996 Sierra release developed by Impressions. It very much involves micro-management, although it is less about statistics but more about tightly managing a space transport empire. Very, very tough game to beat. Only problem? It won't really work on Windows XP, and has troubles with Windows 98. It was made for Windows 3.1 and Win 95.
Another Impressions relase is Detroit about the car industry.
Guroadrunner 14:10, 24 March 2007 (UTC)