[TUHS] Use of "{}" in the Shell?

[Warner Losh via TUHS]

On Tue, Aug 4, 2026, 1:23 PM David Barto <barto at kdbarto.org> wrote:

> Then why does
> echo me; echo $$
> ( echo parens ; echo $$ ; )
> { echo brace; echo $$ ; }
>
> Always echo the same pid?
>
> me
> 46999
> parens
> 46999
> brace
> 46999


Because {} doesn't fork a shell.

Warner


> > On Aug 3, 2026, at 11:47 PM, Arnold Robbins via TUHS <tuhs at tuhs.org>
> wrote:
> >
> > Warner Losh via TUHS <tuhs at tuhs.org> wrote:
> >
> >> I've not examined the source to Thompson shell closely to know if it
> >> secretly does this (and that's why Steve Bourne implemented it), or if
> >> that's something Bourne invented.
> >
> > Braces are also allowed where "do" and "done" are.
> >
> > I have always suspected, but never bothered to verify, that this is
> > the case so that shell scripts could look more like C if one wanted
> > them to. For example, in Bash:
> >
> > $ for ((i = 1; i <= 3; i++))
> > > {
> > >     echo $i
> > > }
> > 1
> > 2
> > 3
> >
> > Arnold
>
>