Re: extension of file-test primitives?

[Peter & Kelly Passchier]

On 08/23/2017 07:36 PM, Greg Wooledge wrote:
> Second, you proposed test -fx.  But this collides with existing
> multi-character test options.  Specifically, test has the options -e,
> -f, and -ef.  So your proposal of letter-concatenation would take
> the -e and -f options and squash them together into -ef, which would
> collide with the "two files are hard links to the same inode" option.
>
> Likewise, the unary options -n and -t would combine into -nt which
> collides with the binary "mtime is newer than" option.
>
> Sure, you might argue that there is no reason to combine -e and -f
> together, since one implies the other; or that no sane person would
> ever combine -n and -t together; but that's not the point.  The point
> is to avoid reader confusion.  It's already bad enough that the -a
> option is overloaded and has two completely different meanings.  Let's
> not compound that mistake.

I was the one proposing combining the UNARY operators in a way like -fx, 
and your -a example shows that there is a precedent. Unary and binary 
operators are different, so there is no confusion for the parser or for 
the user. It would just work for the person who would like to use it. 
The combining would only be allowed (and only make sense) for the unary 
operators, and it would lead to a  much cleaner and more readable 
source. It is also in line with common GNU combining-short-options 
syntax. Users might even expect this to work already.

This change would not hurt backwards compatibility and enhance bash in a 
clean way, making things more readable where they would/could be used.

Peter