Re: Why does close_stdout close stdout and stderr?

[Paul Eggert]

Bruno Haible wrote:
> For the other case, we can introduce, next to the !SANITIZE_ADDRESS test,
> tests for
>    getenv ("LD_PRELOAD") != NULL
>    getenv ("ASAN_OPTIONS") != NULL
>    getenv ("TSAN_OPTIONS") != NULL
>    getenv ("MSAN_OPTIONS") != NULL
>    getenv ("LSAN_OPTIONS") != NULL
> We can add more such environment variables as needed. getenv() lookups
> don't make system calls; so they are cheap.

A less-intrusive possibility is to suggest to people writing specialized 
log-to-stderr environments that they use an (optional) environment variable 
ERROR_FD to specify which file descriptor to log to (with the default being file 
descriptor 2), and that they test coreutils with ERROR_FD=3 and with file 
descriptor 3 open to their error log. That way, coreutils would not need to be 
modified, and could even get rid of the !SANITIZE_ADDRESS hack after 
AddressSanitizer adopts this approach.