Re: [Help-bash] Separation of compound commands

[Nicholas Chambers]

On 3/14/17 11:24 AM, D630 wrote:
> Why does A work, but B doesn't?
>
> # A
> { { :; } }
> if :; then if :; then :; fi fi
> { (:) }

Braces can be nested, however statements/commands need to be terminated. 
That is why the first works. I am not sure what part you don't 
understand in the second example. For the third, bash can tell that the 
statement : is over since it is wrapped in ()'s. If it didn't have those 
you would need a semicolon again (ie { :; }).

> # B
> { (()) }
> { [[ 1 ]] }

(()) is a very different kind of statement than (:). (()) is for math. { 
(()); } works. { ( (()) ) } works. { (( 3 + 4 )); } works. Same with [[ 
1 ]]. It is a statement, so it needs some kind of delimiter for bash to 
say its finished. Again, { ( [[ 1 ]] ) } works, and { [[ 1 ]]; } works.

--
Nicholas Chambers
Technical Support Specialist
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1.800.444.9267
www.lightspeedsystems.com