Re: [Help-bash] Understanding read -r

[Dan Douglas]

On Thursday, October 04, 2012 05:25:55 PM Eric Blake wrote:
> On 10/04/2012 05:16 PM, Bob Proulx wrote:
> 
> >> { var=$(</dev/stdin); } <<EOF
> 
> > 
> > I personally dislike the use of /dev/stdin and the others because they
> > are non-portable across kernels and cause me trouble.
> 
> Bash special-cases /dev/stdin so that it works even if your kernel
> doesn't support it.  Of course, that special casing is only applicable
> to situations where bash is opening the file, and not where you pass the
> string '/dev/stdin/ as an argument to some other program, so I tend to
> agree with your analysis that it gets even harder to use when it works
> in some, but not all, contexts within the same machine.

Oh it applies to builtins opening the file passed as an argument too? I 
thought it was only special redirection syntax (like in this case). If that's 
true I might use the tee loadable more frequently.

> >> var=<<EOF
> >> ...
> >> EOF
> >>
> >> This is optimized to happen in memory with no temporary file.
> > 
> > Looks like a nice feature.
> 
> How is it any different from:
> var="...
> "

Just in the handling of escapes and nested quotes. I imagine the quoted 
delimiter variant is more useful. Example usecase:

defaultTrap=<<'EOF'
...
EOF
...

trap "${var:-$defaultTrap}" EXIT
...

-- 
Dan Douglas

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