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Re: Why are curly braces different than parens for cmd grouping?


From: Sven Mascheck
Subject: Re: Why are curly braces different than parens for cmd grouping?
Date: Thu, 6 Aug 2009 01:08:59 +0200
User-agent: Mutt/1.5.13 (2006-08-11)

Chet Ramey wrote:
> Linda Walsh wrote:

> > A previous note had me wondering why the syntax for using
> > curly braces to group expressions wasn't able to be the same as
> > using 'paren's.
> 
> Braces are reserved words.  Parentheses are operators.  Blame
> Steve Bourne.

I wonder about the motivation, or was it just an "oversight"?

Some tried to adjust this,

- You did so in bash-1 (just found out by coincidence),
  although blanks were required, "{ cmd }".

- D.Ritchie made them operators in the svr2-derived V8 shell,
  where "{cmd}" works.

- and the SUS rationale to the command language explains that
  this step was delayed for portability reasons but left it open,
  "It is possible that a future version of the Shell [...]"




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