Re: [DOC] Incomplete explanation about the regex =~ operator

[Greg Wooledge]

On Thu, Jan 17, 2019 at 07:53:09AM +0100, kevin wrote:
> I looked at Greg Wooledge's site 
> <https://mywiki.wooledge.org/BashGuide/TestsAndConditionals#Conditional_Blocks_.28if.2C_test_and_.5B.5B.29>:
> 
> 
>    Since *[[* isn't a normal command (like [ is), but a /shell
>    keyword/, *it has special magical powers*. *It parses its arguments
>    before they are expanded by Bash and does the expansion itself*,
>    taking the result as a single argument, even if that result contains
>    whitespace. (In other words, [[ does not allow word-splitting of its
>    arguments.) /However/, be aware that simple strings still have to be
>    quoted properly. [[ treats a space outside of quotes as an argument
>    separator, just like Bash normally would.
> 
> Unfortunately, there is no example that shows how *[[* differs from the
> usual shell operation.

https://mywiki.wooledge.org/BashFAQ/031 may be a better reference.