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IR Blaster works at command line, but not in MythTV
http://forum.linhes.org/viewtopic.php?f=6&t=15802		 Page 1 of 1
Author:  Das Hammer [ Sat Jul 07, 2007 8:02 am ]
Post subject:  IR Blaster works at command line, but not in MythTV
Title pretty much says it. I know the hardware is working because I can execute /etc/irblaster/channel_change.sh 123 and the STB will change channels. I entered this script location into the "external channel change command" field. I went to Input connections then /dev/video0 (S-Video 1). I created the channel with the channel editor rather than importing them from listings from the Video Sources menu (zap2it seems to be down right now).

I first tried executing the /etc/irblaster/channel_change.sh script with the mythtv user and it worked, so it is not a permission problem.

I also made my own script /etc/irblaster/bogus.sh which just outputs the date and time into /etc/irblaster/bogusoutput.log I can execute this script at the command line and the bogusoutput.log is populated with the date/time of every time that I execute it. However, if I use that script as my external channel change command, it does not execute when I change channels in MythTV.

I'm using a serial IR blaster, but have a PVR150 with the receiver/blaster. I ran /usr/local/bin/lirc-reconfig.sh and selected the PVR150 Gray remote (the one without the IR blaster) just to see if it was trying to use the other blaster by default.

I don't know what else to look for at this point.

I may try using the PVR150's blaster instead.
Author:  tjc [ Sat Jul 07, 2007 9:35 am ]
Post subject: 
Any time you have a script which works when run interactively but "doesn't work" in some other circumstance, the first thing to ask yourself is "what's different"? The #1 culprit is usually your environment variables. (Secondary things include "Am I running it as the same user?", "Am I specifying the full pathname to the script?", "Is it being run in a different directory?")

To debug differences in the environment variables:

1) Capture the stdout/stderr output of the script somehow. One way is to add a line like this near the beginning of the script:
Code:
exec >/tmp/mydebugging.log 2>&1

This is for a shell scripts. For Perl, Python, ... you need to do something equivalent.

2) Record the current environment in that log. This means adding a line like this after the exec line shown above:
Code:
env

Or possibly like this to make comparisons easier:
Code:
env | sort


3) For the "where am I really" issue alluded to above add a line like this after the exec:
Code:
pwd


Once you determine what the differences are you can fix them, in the script, as "bad assumptions about ..."
Author:  bruce_s01 [ Sat Jul 07, 2007 4:07 pm ]
Post subject: 
Perhaps I'm asking the stupidly obvious question :) , did you put the channel number to be sent to the STB in the Frequency field on the second screen of the channel editor screen where the Brightness etc. sliders are?

Bruce S.
Author:  tjc [ Sat Jul 07, 2007 8:53 pm ]
Post subject: 
Knew I'd forgotten something... ;-) "Is it being called with the same arguments?"

4) To see that add a line like this after the exec:
Code:
echo "Args: $*"
Author:  Das Hammer [ Sat Jul 07, 2007 9:33 pm ]
Post subject: 
bruce_s01 wrote:
Perhaps I'm asking the stupidly obvious question :) , did you put the channel number to be sent to the STB in the Frequency field on the second screen of the channel editor screen where the Brightness etc. sliders are?

Bruce S.


I'm glad you asked that, sir, because I did not. I thought the "Channel Number" on the first screen took care of that. Thank you! I just tried your suggestion and it worked.

tjc, I thank you for your help as well; not only on this topic, but my other ir blaster issue. You have helped me learn a lot more than I planned on, but it was worth it.
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