[BRLTTY] introduction

[Dave Mielke]

[quoted lines by kendell clark on 2016/03/19 at 14:16 -0500]

>I'd be happy to capture a core dump, if I had any idea how. Can you give me 
>instructions? 

The usual way a Linux system is configured, core dumps are disabled. To enable 
a full core dump, execute this command from the same shell that you're starting 
brltty in:

   ulimit -c unlimited

You can confirm the current setting with: ulimit -a

You should find the core dump (after the crash, of course) in /. It'll be named 
something like core.pid (where pid is the process id that caused the dump).

Again, remember to compress it before attaching it to an email.

>I don't have tools like abrt, which help in this process, but I can follow 
>manual instructions. 

What I'm looking for is the backtrace of the crash. The best way to get that 
backtrace is by using gdb. If you can capture this then just sending the 
backtrace would be better than sending a whole core dump and brltty executable.

   Linux> gdb /path/to/brltty-executable /path/to/core-file
   gdb> bt
   gdb> q
   linux>

An easy way to capture the output from gdb is to wrap the whole thing within a 
script session. Script is a command that starts a subshell and records console 
output into the file typescript. So:

   linux> script
   script> gdb /path/to/brltty-executable /path/to/core-file
   gdb> bt
   gdb> q
   script> exit
   linux>

Then you should have a file named typescript that contains the backtrace.

>I didn't even know tty0 existed, I thought tty1 was the first available tty. 

Technically, there isn't. tty0 is special, and refers to whichever is the 
current tty.

>The first thing I do after starting brltty is to switch to tty2 using 
>control+alt+f2, at which point brltty is killed, although I'm not a hundred 
>percent sure it's the console switch that does it. 

Try waiting a couple of minutes before switching in order to create a large 
enough time difference that events can be matched up. Also, maybe execute the 
date command just before switching.

-- 
Dave Mielke           | 2213 Fox Crescent | The Bible is the very Word of God.
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