Re: Modify buffering of standard streams via environment variables (not LD_PRELOAD)?

[Carl Edquist <edquist@cs.wisc.edu>]

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On Thu, 18 Apr 2024, Zachary Santer wrote:

> On Wed, Mar 20, 2024 at 4:54 AM Carl Edquist <edquist@cs.wisc.edu> wrote:
>>
>> However, if stdbuf's magic env vars are exported in your shell (either 
>> by doing a trick like 'export $(env -i stdbuf -oL env)', or else more 
>> simply by first starting a new shell with 'stdbuf -oL bash'), then 
>> every command in your pipelines will start with the new default 
>> line-buffered stdout. That way your line-items from build.sh should get 
>> passed all the way through the pipeline as they are produced.
>
> Finally had a chance to try to build with 'stdbuf --output=L --error=L 
> --' in front of the build script, and it caused some crazy problems.

For what it's worth, when I was trying that out msys2 (since that's what 
you said you were using), I also ran into some very weird errors when just 
trying to export LD_PRELOAD and _STDBUF_O to what stdbuf -oL sets.  It was 
weird because I didn't see issues when just running a command (including 
bash) directly under stdbuf.  I didn't get to the bottom of it though and 
I don't have access to a windows laptop any more to experiment.

Also I might ask, why are you setting "--error=L" ?

Not that this is the problem you're seeing, but in any case stderr is 
unbuffered by default, and you might mess up the output a bit by line 
buffering it, if it's expecting to output partial lines for progress or 
whatever.

Carl