Re: Another 'What's the diff Q" (LDo will like this)

On 17.09.2024 07:37, Kenny McCormack wrote:

(bash)  What is the difference between << and <<<, from a functionality
POV?  I.e., is there anything you can do with one but not the other?
 
I'm talking about this:
 
$ cmd << 'EOF'
...
...
EOF
$
 
vs.
 
$ cmd <<< '
...
...
'
$
 
Of course I know, as does everybody, that << is legacy and <<< is new, but
it begs the question: Why was <<< added to the language?

The '<<<' is basically only a convenience syntax for one-liners.

When it had (first) been introduced by Kornshell there was a slight
difference between the two, '<<' and '<<<'; IIRC, the '<<<' did not
create a '\n'. (I had discussed the feature with DGK the days when
it had been introduced. The result, DGK's decision, is what you see.)

 
Note that I use both constructs, as the mood suits me, but I just got to
thinking that maybe <<< doesn't actually add any new functionality.

It's actually a restriction since it doesn't allow (e.g.) to control
variable expansion (as is possible with escaping the tag ('EOF' in
your example, which prevents exüpansion, vs. unquoted/unescaped EOF ).

And, of course, Kornshell allows yet more control features with '<<';
see its man-page for the '<<#' variant.

Janis