Wikipedia:Reference desk/Archives/Computing/2006 September 13

< September 12	Computing desk archive	September 14 >

Humanities Science Mathematics Computing/IT Language Miscellaneous Archives

The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions at one of the pages linked to above.

< August September October >

September 13

Clisp library

Hi, I just downloaded clisp and am wondering how I can read the syntax (and possibly the actual function bodies) of the built in LISP functions.

The syntax for calling them is probably given in the documentation for your Lisp system. The actual function bodies are quite possibly written in another language and/or compiled into machine code, so they aren't necessarily accessible in a useful fashion. If you are talking about CLISP as described here, its built in functions are presumably written in C and can be seen in its publicly available source code. There is no guarantee, however, that the form of those implementations is at all conducive to understanding them in terms of their Lisp behavior. --Tardis 20:03, 26 September 2006 (UTC)

Windows XP how to get back the entrypted files when the owner user is deleted?

Hi, I had some files that were owned by a user. I made the folder private and chose to entrypt. However I moved these files to a different folder and then deleted the XP user. Now I am unable to open these files as they are encrypted. Even though I created the user with the same name, I am unable to uncheck the option of entrypt in the properties of these files. I get a message "Access is denied." How can I fix this issue? regards,

You can't, that's one of the caveats of the Windows encryption system. The key is irrevocably tied to the User ID. See the relevant portion of the EFS article for more. — Lomn | Talk 14:52, 13 September 2006 (UTC)

Knoppix? Crazy Fox (T|C|E) 23:59, 13 September 2006 (UTC)

Is no use in this case, as the user's private key will have been deleted when the account was. If an account had been set up as a recovery agent (and in XP none are by default, unlike with Windows 2000 where the administrator account is automatically one) then that account could be used to recover the files, but presumably our questioner hadn't done this. There are ways of getting at EFS-encrypted files in Linux, but they still require the relevent user account to exist in Windows. -- AJR | Talk 01:03, 14 September 2006 (UTC)

MathCad 12

I purchased a copy of MathCad 12 just before MathCad 13 was released and installed it under Windows XP Service Pack 2. It installed and worked okay. I stopped using it for about two months. When I tried to run it today it would not run at all even after reinstallation. Does anyone know if recent Windows XP automatic updates could be responsible and if they may have blocked or disabled it and what would be the best way to overcome this problem? Adaptron 15:26, 13 September 2006 (UTC)

ask them. Jon513 16:34, 13 September 2006 (UTC)

Thanks. Looks like it was the "Installing Windows XP SP2 Disables C_Dilla Service" issue. Adaptron 21:29, 13 September 2006 (UTC)

Ant, jrc and classpaths in subdirectories.

I'm using Apache Ant to build a large Java project which includes some Jasper Reports. I'm modifying the project to build the reports and ship them in the resultant JAR archive. The main JAR file contains this call:

<ant dir="report" target="jar"/>

the jar target calls compile-base as well as compile-reports, the new target I just added. compile-reports reads, in its entirety (from report/build.xml:

 <target name="compile-reports" depends="compile-base">
   <taskdef name="jrc" 
            classname="net.sf.jasperreports.ant.JRAntCompileTask"> 
     <classpath>
             <pathelement path="${base.classpath}" />
             <pathelement path="${buildclasses}"/>
     </classpath>
   </taskdef>
   <jrc srcdir="reports/"
        destdir="${buildclasses}"
        excludes="**/test/*.java,**/Test*.java,*.bak">
     <classpath>
       <pathelement path="${base.classpath}" />
       <pathelement path="../lib/jasperreports-1.2.0.jar"/>
       <pathelement path="${buildclasses}"/>
     </classpath>
   </jrc>
 </target>

Here's the thing. If I go into report/ and run ant jar, the reports generate properly. If I run ant build from the top-level directory, which, as shown above, calls ant jar in the report/ directory, it fails with this message.

BUILD FAILED

build.xml:131: The following error occurred while executing this line:

report/build.xml:189: org.apache.commons.logging.LogConfigurationException: org.apache.commons.logging.LogConfigurationException: org.apache.commons.logging.LogConfigurationException: Invalid class loader hierarchy. You have more than one version of 'org.apache.commons.logging.Log' visible, which is not allowed. (Caused by org.apache.commons.logging.LogConfigurationException: Invalid class loader hierarchy. You have more than one version of 'org.apache.commons.logging.Log' visible, which is not allowed.) (Caused by org.apache.commons.logging.LogConfigurationException: org.apache.commons.logging.LogConfigurationException: Invalid class loader hierarchy. You have more than one version of 'org.apache.commons.logging.Log' visible, which is not allowed. (Caused by org.apache.commons.logging.LogConfigurationException: Invalid class loader hierarchy. You have more than one version of 'org.apache.commons.logging.Log' visible, which is not allowed.))

From what I can google up, the above is caused by some malfeasance with classloaders. I'm not doing anything with classloaders. I didn't even know what classloaders do until I had to learn to deal with this, and now I wish I never had...

If I add the following to the top-level build.xml, above the call to <ant dir="report" target="jar"/>, it still fails.

<ant dir="report" target="compile-reports"/>

However, if I add this, it runs just fine.

<exec dir="report" executable="/usr/bin/ant">
  <arg value="compile-reports"/>
</exec>

This is, of course, a grotesque hack. What did I do to offend the build system so grievously as to require this? I've spent the last hour and a half switching around statements mindlessly, to no avail. Am I stuck with this wart in the middle of my master build file? grendel|khan 21:09, 13 September 2006 (UTC)

Authentication in Apache

I'm trying to enable digest authentication in Apache, but without any luck (basic authentication works). Could someone provide an example of what a .htaccess (I don't have access to the configuration file) should look like? Also, when creating a password file with htdigest, one parameter is realm. What is that? It wasn't required for basic authentication. Thanks! —Bromskloss 21:31, 13 September 2006 (UTC)

• Is this helpful? --jpgordon^∇∆∇∆ 21:46, 13 September 2006 (UTC)

• No, unfortunately not. It only touches upon the so-called basic authentication. —Bromskloss 07:52, 14 September 2006 (UTC)

Hard Drive and Virus problems

Well, I've been running Windows after my PSU caught on fire, and it must have corrupted my OS because of the long boot ups, but nothing else than that. So yea, I’ve been finding a lot of trojans and worms on my computer, and I've looked at Symantec's webpages for the specific worm/trojan/virus, and they tell me to look under regedit to see if it edited some of the registry values. All have lead to dead ends... and I've scanned a million times with Nod32 and AVG free edition. Both can never scan the boot sectors or system memory, and Nod once showed errors on all files (either was locked, or there was an error). So, could this be the work of virus sabotage?

I booted my PC around 7 pm MT today, and it was an unusually long boot up. It booted to desktop, but no shortcuts or the system tray showed. It paused, then started to kick in gear, but then I heard my hard drive make some squeaky sounds like a mouse. Is this bad? If so, could a virus have done this? I'm going to reformat, but if this squeak indicates my HD is bad, then... I guess I'm getting a new HD (which had a lot of music I bought via WMP).

Ok, if there isn't a problem, then I'm going to get an external HD, copy my music folder to that (along with some other stuff), and then reformat. But I was wondering, if I'm crawling with bugs like I think I am, is there a high risk one of those pesky viruses or w/e will get on my external HD? If so, it shouldn't be hard to remove with proper anti-virus removal, right? Big thanks to anyone who replies.--Hellogoodsir 02:07, 14 September 2006 (UTC)

That's a good idea. It's probably safe to assume that the virus only affected the OS and had not imbedded itself into your music and such. But scan to make sure. --Proficient 06:06, 15 September 2006 (UTC)