[mythtv-users] channel changes via script suddenly stopped working--diagnose help

[Paul Wootton]

On 13 Apr 2013, at 20:53, Larry Roberts <mythtv at american-hero.com> wrote:

>> Looking at the code, you're doing an append '>>' to the cc.log, so if the script were running twice you'd see two lines in the log, so forget that.  I'd be tempted to suggest something really weird like an odd multi-path reflection, but that wouldn't explain why it's OK from the command line.   Are there any other IR blasters nearby that are also triggering?  Do you have any other machines on the network that might be doing some sort of remote irsend?  What happens if you firstly rename rename the irsend executable and then the equivalent name in the code.  This way you can  discount it being called from elsewhere.  Other things I'd try are rebooting everything (perhaps with a power cycle); putting the IR blaster in a cardboard tube and taping it to the receiver so no stray IR gets in, and calling an exorcist (your milage may vary).
>> 
>> -- Paul --
>> _______________________________________________
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> Do you happen to know the # of a good exorcist?  I shutdown and pulled power from the box.  The IRblaster is taped to the front of the cable box and its in a utility closet with nothing else around. I'm really at a loss as to why it will work perfectly from the command line (I'm doing this a root) but will not work when myth does it.  Is it actually mythbackend that calls the script?  I have mythbackend running as root but I'm not sure if thats the user that spawns it or not.  I haven't messed with it in so long I honestly dont recall how I set it up.
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> Do you happen to know the # of a good exorcist? 
Yup, shall I send him round? :-)

OK - from the details above I'd say it's unlikely to be external influences.
I'd regard running the mythbackend as root as 'unusual', but I can't see being harmful.  Next thing I'd check is whether the cc script is really being run as root; and to that end I'd change the line that says 

print CCFILE "$channel". "\n";

to something like

print CCFILE scalar localtime(), " $< $>  $channel\n";

so that you can see the exact time that the script was called, it's UID ($<) and EUID ($>), and the command.  I'd expect that UID and EUID are both 0 for you.  

I'd be pretty sure that the script is being called from the backend - you don't have any slave backends do you?

If none of the above reveal any problems then next I'd say look at de-installing/re-installing lirc, but that's beginning to get into desperation measures.  The only other thing I'd wonder is - is there a physical fault in the IRblaster, but the fact that the script works from the command line suggests not. 
[When I worked on Aircraft Sims, the rule for fault finding was "If it isn't the cables it's the cables - you just haven't checked hard enough]

After that I'm out of ideas for the moment - I'll see if anything tickles the subconscious while I watch an old recoding of Guitar Heroes at the BBC on my mythbox.

-- Paul --