Loading a most stubborn application at startup

Question

Hi all,
I received quite a bit of help on irc, however I have nonetheless been unsuccessful in making this work.  Essentially I have written some software that manages various usb devices as well as a script that runs the application and then logs the output from stdout and stderr.  Running this application from the cli after logging in works great.  Attempting to run the application during boot however does not work (it segfaults).
I have tried many things: writing a bash script and running it from rc.d (via daemons in rc.conf), attempting to run the script directly from rc.local, attempting to run the script using screen from rc.local, performing various modifications to my /etc/inittab such as using this command as described in the wiki x:5:once:/bin/su - -- PREFERRED_USER -l -c 'EXECUTE SCRIPT HERE', etc.
None of these worked.  I figured that, before I quit entirely, I might ask the community to see if anyone else had any ideas.  Any help is greatly appreciated!!!

Answer 1

rowdog wrote:
anstmich wrote:Something to note, however, is that the program fails when run in the background (i.e. "/home/user/app &")
Why? That's probably the first issue to track down. Is this "software" a program that you wrote? What language?
Long running processes are normally written as daemons. Wikipedia has an overview of the usual approach at
http://en.wikipedia.org/wiki/Daemon_%28 … of_daemons
Yes this is an application that I wrote in C.  I tried daemonizing it and that did not work, which I am guessing somehow relates to the fact that it doesnt like being run as a background prcoess.  Beyond using libusb, the only other "libraries" used are those provided standard with C (i.e. string.h, stdio.h, stdlib.h).  Also, when I did daemonize it, if I called /etc/rc.d/app start it would work just fine, just not during boot, however.  I will do some reading though, thanks! 
I agree with lives2evil,
This will get a lot more visibility from the coders over at Programming.  Moving....
I would wager real money you are using dereferencing  null pointer some place.  Maybe some function that fails because the USB in question is not yet set in time for your script?  Set up some logging and pour a bunch of telemetry out to the debug log to see what is happening.
You might want to put the source up on pastebin and provide a link.
I doubt it is a null pointer (I do quite a bit of error checking for this).  My guess, though, is that you are right about the USB.  There must be something that libusb needs -- an environment variable or something. 
If I try putting in a long delay (30+ seconds) in the python (or bash) script that runs my application, although it pauses successfully, the application called still fails.  Furthermore, if I immediately log in and run the script manually, everything works fine.  This would lead me to believe that there is perhaps a problem detaching the kernel USB driver? Im not sure what else could be different before and after logging in.
Thanks for the help!