Re: why did coprocs fd not exist, in this sample submissed on an issue as answer

[Greg Wooledge]

On Thu, Sep 30, 2021 at 09:49:52PM +0200, Alex fxmbsw7 Ratchev wrote:
> i think the middle chapter is the because, sorry i understand your english
> only modestly
> in this case of code i can easily aviod coproc then
> thanks you

You tried to do this:

one=( $( < /proc/fd/$ser ) )

The redirection from /proc/fd/$ser occurs in a subshell, because of the
command substitution $( ).  Chet quoted the part of the manual that says
coproc FDs are not available inside subshells.

For anyone who's confused about this: $( ) always forks (creating a
subshell), even if you're using the $(< file) feature as a replacement
for $(cat file).

Maybe you should consider one of these replacements:

read -ra one <&"$ser"

mapfile -t one <&"$ser"

I don't know what your writing process is sending, so you'll have to
choose based on that knowledge.  The first one is closest to your
original command.