Re: symlink chain.

[Ray Andrews <rayandrews@eastlink.ca>]

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"
    zsh-5.0.7-165-g2194da1
    /usr/bin/zsh -> /usr/local/bin/zsh-5.0.7-165-g2194da1


    $ whence -mas "*zsh*"
    zsh-5.0.7-165-g2194da1
    /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
    /usr/local/bin/zsh,3,bart-fix-TRAPDEBUG
    /usr/local/bin/zsh-2014-11-14
    /usr/local/bin/zsh-5.0.7-109-g2598010
    /usr/local/bin/zsh-5.0.7-112-g49d6aac
    /usr/local/bin/zsh-5.0.7-125-g167a15a
    /usr/local/bin/zsh-5.0.7-136-g0a07ffd
    /usr/local/bin/zsh-5.0.7-138-g247f754
    /usr/local/bin/zsh-5.0.7-159-g89c692e
    /usr/local/bin/zsh-5.0.7-161-g1cd8023
    /usr/local/bin/zsh-5.0.7-165-g2194da1
    /usr/local/bin/zsh-5.0.7-dev-0
    /usr/local/bin/zsh-RayStyle1
    /usr/local/bin/zsh.old
    /bin/zsh4
    /bin/zsh5

... 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.