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Re: symlink chain.

On 01/02/2015 09:03 PM, Bart Schaefer wrote:
On Jan 2,  5:08pm, Ray Andrews wrote:
} Subject: Re: symlink chain.
} Needless to say, I have no idea if this is sound, however:
}      /* With -m option -- treat arguments as a glob patterns */
} //    if (OPT_ISSET(ops,'m')) {
}      if (OPT_ISSET(ops,'m') && **argv != '/' ) {
} ... seems to work.

I wouldn't use the word "work" exactly.  All that does is turn off the
pattern matching entirely.  You're probably next going to complain that

% whence -m /\*/bin/zsh

I repeat that I have no idea if that is sound, I'm just fooling with it. But I haven't broken it here (yet).

   $ whence -mas "/usr/bin/zsh"
   /usr/bin/zsh -> /usr/local/bin/zsh-5.0.7-165-g2194da1

   $ whence -mas "*zsh*"
   /usr/local/bin/zsh -> /usr/local/bin/zsh-5.0.7-165-g2194da1
   /usr/bin/zsh -> /usr/local/bin/zsh-5.0.7-165-g2194da1
   /bin/zsh -> /usr/local/bin/zsh-5.0.7-165-g2194da1

... so pattern matching is still working, so far.

should return /usr/bin/zsh and /usr/local/bin/zsh, or somthing of the
kind.  This is just abusing the purpose of "whence", which is intended
to tell you what a path search would find for a simple command name.

Well, what it 'should' be used for is subjective, and of course my views on
that are very junior.  I want it to give me every command that matches the
pattern, and not to crap out if  -m is given, just because a full path is
specified. Ditto with -a. And I'd like being able to use it to see symlink chains.
I think all of that makes the command more intuitive and far more useful
even  if it is a breach of tradition.

If we *really* want this behavior -- which I submit that we don't, as
we're wandering into silly territory like whence -m '*bin*' returning
all commands in all directories named "bin",

Speaking for myself, that's not something I'd begin to want. I want it to do what
it advertises itself to do, but with no gotchas.  I'd not call that silly.
so we should stop futzing
around with "whence" -- then the correct thing is rewriting the hash
table scan to look at both the keys and the values when doing the
pattern matching.

Which has ramifications beyond "whence" because it uses the same hash
table scan routines as everything else.  I confess I'm actually a bit
surprised that PWS was willing to hack up something as deeply involved
in the internals as xsymlinks() [in which we just finished fixing other
obscure bugs] in order to implement whence -S.

Of course we leave final decisions to you guys as to what can be done safely.
But once I lean how to preserve them, I'll be keeping both of those:

... && **argv != '/' ...
changes, cuz they sure look good to me. (And the symlink chain once I learn
how to import a patch.)  That's presuming a better method isn't forthcoming.

Shell functions exist so that if something like whence doesn't do what
you want, you can write something else that does.

Yup. I had those link-chains displayed with 'namei' just fine, but I still think
it is a natural addition to whence.  You guys know best.

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