bash's globstar considered dumb (** not composable)

[William Park]

I think '**' came into Bash from Zsh.
-- 
William

On Sat, Sep 24, 2011 at 04:17:49PM -0400, D. Hugh Redelmeier wrote:
> In the shell, you can write a kind of regular expression to designate
> all files which match that expression.  For example, "*.c" designates
> all filenames which end in ".c".
> 
> Many years ago, I thought about how the notation ** isn't useful (it
> would just be a synonym for *). and how it could be given another
> interesting meaning.  I thought: why not allow it to match files
> within subdirectories too.
> 
> I mentioned this to Rob Pike and he responded: bad idea because the
> file structure might not be a tree:
> 
> - a DAG (Directed Acyclic Graph) due to hard links for files
> 
> - worse due to symlinks (which I still think of as evil)
> 
> - there was some thought of allowing hard links to directories (hasn't
>   yet happened)
> 
> So I dropped the idea.
> 
> Fast forward a couple of decades: BASH 4 has this very feature.
> Surely not due to my suggestion.
> 
> I tried it for the first time today.  I wrote "**.c".  It didn't work
> the way I expected.  But "**" did.  Huh?  According to
> <http://wiki.bash-hackers.org/syntax/expansion/globs>
> 
>     :V4: when the shell option globstar is set, the glob ** will
>     recursively match all files and directories. This glob isn't
>     "configurable", i.e. you can't do something like **.c to recursively
>     get all *.c filenames.
> 
> The use of the word "configurable" seems really peculiar to me.  For
> one thing, it is configurable: ** only works if you enable the
> "globstar" option.  For another, what they clearly mean is composable:
> you cannot compose it with other regular expression operators (which
> includes literal elements).
> 
> Not being composable seems really really dumb.
> 
> Back to using the awkward but powerful find(1).
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-- 
William
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