Re: heredoc and subshell

[Joerg Schilling <Joerg.Schilling@xxxxxxxxxxxxxxxxxxx>]

Eric Blake <eblake@xxxxxxxxxx> wrote:

> > --- code
> > prefix() { sed -e "s/^/$1:/"; }
> > DASH_CODE() { :; }
> > 
> > prefix A <<XXX && echo "$(prefix B <<XXX
> > echo line 1
> > XXX
> > echo line 2)" && prefix DASH_CODE <<DASH_CODE
> > echo line 3
> > XXX
> > echo line 4)"
> > echo line 5
> > DASH_CODE
> > 
> > --- bash 4.3.42 output:
> > A:echo line 3
> > B:echo line 1
> > line 2
> > DASH_CODE:echo line 4)"
> > DASH_CODE:echo line 5
>
> So, it looks like bash is interpreting this as "first newline that is
> not in the middle of another shell word), and parses the entire $(...)

I would like to get an explanation on what I should understand by:

	"first newline that is not in the middle of another shell word)


BTW: If I replace $(..) by `..` and feed the code to the original SVr4 Bourne 
Shell, I get the same output as you got from bash. I would guess that the bash 
output you added above is correct.

Note that the command substitution is part of a " quoted string and even 
without that, it would need to be parsed first.

The POSIX version from ksh88 (seen on Solaris) behaves the same with $(..) and 
the `..` variant and the same as bash.

The fact that ksh93 behaves different with $(..) and the `..` variant makes it 
obvious that ksh93 has a bug.

Jörg

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