Re: redirection / process substitution fails to read a file descriptor

[Greg Wooledge]

On Sun, Nov 17, 2024 at 12:16:29 -0600, Mike Peters wrote:
> On 2024-11-16 20:35, Greg Wooledge wrote:
> > On Sat, Nov 16, 2024 at 16:35:05 -0600, Mike Peters wrote:
> > >          > exec 3<test.txt
> > >          > cat <&3
> > >          foobar
> > 
> > OK.  This part is straightforward.  Note that you used a command, cat,
> > to write output.  You didn't simply type <&3 without a command.
> 
> You're saying that <&3 on an input line by itself should work? It outputs 
> nothing for me. Effectively the same point as the purpose of this submission. 
> Although <test.txt by itself doesn't output anything for me either.

No, I'm pointing out that you *did* use cat, because you *needed* to.
If you had simply typed <&3 without the cat command, it wouldn't have
worked.

> > >          > exec 3<test.txt
> > >          > echo `< <(<&3)`

Which is why it didn't work here -- there's no cat command.  There's no
command at all.