Should we use [[ or should we use [ when the later will do? (Was: Execution of subsequent commands ...)

From:	Chet Ramey
Subject: Re: Execution of subsequent commands after a command crashes.
Date:	Tue, 3 Feb 2026 09:37:13 -0500

>On 2/2/26 10:29 PM, Robert Elz wrote:

>> ps: it is really dumb to use bash extensions when standard portable
>> POSIX shell code works equally well, "[[ $? -ne 0 ]]" is not in the
>> slightest different from "[ $? -ne 0 ]" and the latter will work in
>> any shell - so use the latter, not the former.

I think it is dumb to publicly call another poster "dumb".

Chet wrote:

>On the other hand, there's no problem with using bash features when
>you're writing a bash script and don't have to be concerned about
>portability.

I've seen posts that say that you should always use [[ in new code,
simply because it is better behaved and can do everything that [ can
do (and better).  I'm not sure I agree with this, but I see their
point.

Personally, I still use [ when it is sufficient, and only use [[ when
it seems appropriate (*), but I realize that this may not be
absolutely best practice.  I certainly don't do this out of any sort
of obsession with "POSIX".

(*) Usually, specifically because I want to use =~

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