CURIOSITATIS CAPTIVUS » computing

Installing RExcelXML from The Omega Project in R

captivus — Wed, 05 Jan 2011 19:14:54 +0000

A quick post to capture the resolution to the past 20 minutes I have spent in frustration trying to install RExcelXML from Omegahat (The Omega Project for Statistical Computing). As this is a source package, the dependencies need to be satisfied manually (which is a bit baffling, frankly — surely there is a workaround for this using a makefile-like facility in install.packages()). The package depends on ROOXML, Rcompression and XML. The solution is two-staged:

> install.packages(c('Rcompression', 'XML'))
> install.packages(c('ROOXML', 'RExcelXML'), repos = 'http://www.omegahat.org/R', type = 'source')

Back to the grind …

DD-WRT on the WRT54G v8

captivus — Sat, 09 May 2009 03:30:24 +0000

DD-WRT is, by far, my favorite third-party firmware for the Linksys WRT54G wireless router. I, personally, have three of these on my network — one as the primary access point and router and two as bridged repeaters — on which I have used several versions of dd-wrt. (I’ve also used Sveasoft and Hyper-WRT on these devices.)

Previously, I have endured spectacular failure when trying to flash version 8 devices. (My devices are all version 2. The Wikipedia article I linked to above explains the differences in the hardware versions.) It turns out, the critical misunderstanding I had related to flashing the stock firmware with vxWorksKiller (prior to transferring the DD-WRT image to the router via TFTP). I did not realize that the upload of vxWorksKiller needed to be done from a special management screen that is only accessible after unplugging the router, holding down the reset button while plugging the router back in, and continuing to hold the reset button for 20 seconds. This implies that the upload should not be done from the default firmware’s upgrade page. This understanding was gained this week when building a PC, and flashing two routers, for a friend of mine.

Given that the preponderance of WRT54Gs on shelves now are version 8.x, this realization bodes well for me in future purchases.

Core Dumps in Ubuntu

captivus — Wed, 06 May 2009 03:25:01 +0000

I resolved this year that I would take time to pursue one of my passions — computer science. As such, I am learning how to write applications for Linux. I’ve just spent 30 frustrating minutes trying to figure out why on earth my deliberate segmentation fault in the small C program I have written is not producing a core dump in Ubuntu 9.04. It turns out that Ubuntu disables core dumps in Bash by default. The fix is simple enough — use the ulimit command to enable core dumps.

bash$ ulimit -c 100

In this case I have enabled core dumps and given them a limit of 100 blocks. Problem solved! Hopefully this makes it into the search engines and helps someone else frustrated by this same issue.

Microsoft PowerToys for Windows XP

captivus — Fri, 27 Oct 2006 00:06:50 +0000

I stumbled upon a fantastic product offering by Microsoft this evening. I believe that the PowerToys program suite used to be sold in stores. It turns out, however, that — in a dramatic shift from their usual policy of extracting every last dollar from their customers — Microsoft has decided to offer the PowerToys for XP program suite free for download! The programs can be found here. Enjoy!