[BRLTTY] introduction

[kendell clark]

hi
I've executed ulimit -c unlimited, and  verified that it took with
ulimit -a. I then restarted brltty, and verified that it has indeed
crashed, or exited, but there's no core file. Where else should I look
for one or can I generate one?
Thanks
Kendell Clark


Dave Mielke wrote:
> [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.
>