Re: Organising conditions

[hancooper]

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Monday, August 2, 2021 2:23 PM, Greg Wooledge <greg@wooledge.org> wrote:

> On Mon, Aug 02, 2021 at 01:52:00PM +0000, hancooper via wrote:
>
> > I am using some conditions and would like some assessments on the 
> > following. For instance, are
> > they all valid?
>
> > if [[ -d "$dir" && ! $list_raw ]]; then
> > tmpfile=$oldfile
> > fi
>
> > if [[ -d "$dir" ]] && [[ ! $list_raw ]]; then
> > tmpfile=$oldfile
> > fi
>
> > if [[ (-d "$dir") && (! $list_raw) ]]; then
> > tmpfile=$oldfile
> > fi
>
> Those three are fine. Pick whichever one you like.
>
> > if ([[ -d "$dir" && ! $list_raw ]]); then
> > tmpfile=$oldfile
> > fi
>
> This one is not advised. The parentheses create a subshell, which forks
> a child shell process. This is simply unnecessary. It's not even adding
> to readability.

Do (-d "$dir") and (! $list_raw)  also fork a subshell?  I would use it for 
readability.
Is it fine to fork subshells when using conditions as I do?  I do not know much 
about
whether forking of subshells in bash is good, bad, or whatever.