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From: Janis Papanagnou <janis_papanagnou+ng@hotmail.com>
Newsgroups: comp.unix.shell
Subject: Re: Different variable assignments
Date: Sat, 12 Oct 2024 23:56:33 +0200
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On 12.10.2024 23:50, Lawrence D'Oliveiro wrote:
> On Sat, 12 Oct 2024 23:47:34 +0200, Janis Papanagnou wrote:
> 
>> '<(...)' executes the command indicated by '...' and provides a file
>> descriptor, something like '/dev/fd/5', which (being effectively a
>> filename) can be redirected to the 'read' command.
> 
> It’s an actual file name. The process treats it as just another filename 
> argument.

Exactly. (That's what I was saying.) '/dev/fd/5' acts like a file/path
name (but only on systems that support /dev/fd mechanism).

> The fact that it encodes a file descriptor is something OS-
> specific, that only code that wants to create such names (like the shell) 
> has to worry about.
> 
>> The shell's 'read' command doesn't read from files but from stdin
> 
> It can read from any file currently open for reading.
> 
>> So it's no "extra" '<' ...
> 
> Ah, I see. Instead of “< <(«cmd›)”, you could have just written 
> “0<(«cmd»)”.

No.

(1388)$ read <(cat hello_world)
ksh: read: /dev/fd/3: invalid variable name
(1389)$ read < <(cat hello_world)
(1390)$ echo $REPLY
Hello world!
(1391)$ read 0<(cat hello_world)
ksh: read: /dev/fd/3: invalid variable name

Janis