Re: Comments on bash 5.2's undocumented <(<file) and weird >(<file)

[Dale R. Worley]

Emanuele Torre <torreemanuele6@gmail.com> writes:
> Bash 5.2 apparently added  <(< file)  that expand to the path to a fifo
> (openable only for read on BSD) to which the contents of file are
> written to, without documenting it.

I suspect that this is a consequence of

       The  com‐
       mand  substitution  $(cat  file)  can be replaced by the equivalent but
       faster $(< file).

(Which oddly enough, I suggested for Bash some decades ago.)  In the
latter form, Bash doesn't set up a subprocess and then read the pipe
from it but instead just reads the named file.  Or rather, that was the
initial implementation.  I suspect that the code has been updated so
that an "inner command" of "< file" now copies "file" to stdout (as if
it was cat), and the various results you see are based on what the
parent process does with that output.

Dale