Re: [Help-bash] The difference between 'if cond; then' and 'cond && {'

[Peng Yu]

On Tue, Dec 4, 2018 at 7:11 AM Greg Wooledge <address@hidden> wrote:
>
> On Mon, Dec 03, 2018 at 04:27:57PM -0700, Bob Proulx wrote:
> > Precedence in the shell is strictly left to right for && and ||.
> > Therefore one can say:
> >
> >   some_cond && {
> >     do something1
> >     do something2
> >   } || {
> >     do something3
> >     do something4
> >   }
>
> Bad!
>
> >   $ true && echo yes || echo no
> >   yes
>
> BAD!
>
> https://mywiki.wooledge.org/BashPitfalls#pf22
>
> Don't do that.

I don't think this guideline is complete. If the then-branch and
else-branch guarantees to have return status 0, then `some_cond && {
do something } || { do something }` can be used according to this
guideline.

However, the real problem is that the following will return a non zero
status, whereas if-then-else always return a 0 status when "do
something" guarantees to be correct.

false && { do something }

-- 
Regards,
Peng