Re: suggestion: $LS_ARGS

[Harald Dunkel]

Hi Eric,

On 02/23/18 15:01, Eric Blake wrote:
> On 02/23/2018 02:14 AM, Harald Dunkel wrote:
> > Hi folks,
> >
> > I would like to suggest to introduce an environment variable
> > "LS_ARGS", holding the default arguments to ls (similar to $LESS).
> >
> > This could help to simplify the user environment. You don't have
> > to create clumsy aliases for ls anymore, but you could set
> >
> >      export LS_ARGS="--color=never --quoting-style=escape"
> >
> > in your .bashrc without affecting foreign ls implementations (AIX,
> > OpenBSD, Solaris, etc).
>
> Sorry, but we are discouraging the use of magic environment variables that 
> change default behavior (especially introducing new ones), precisely because 
> they can be a surprise source of breakage to unsuspecting scripts.   Or, if you 
> make the variable magic so that it is only consulted when invoked from an 
> interactive user, so that you ensure you don't break scripts with an 
> unsuspected change to the defaults, then you have to consider how easy it is to 
> discover what your current interactive setup is doing.  But an interactive-only 
> env-var has no more effect than an interactive alias or function wrapper, yet 
> 'type ls' will show you what alias or functions you have set but not what 
> env-vars you have set.  Thus, even though it has the same effect on changing 
> the interactive default, it is action at a distance that is not as easily 
> discoverable to change that default if it is not desired.  So we are unlikely 
> to act on this proposal.

I completely agree with your concerns about magic vars, but
please consider

- there are tons of magic vars in wide use today: LANG and
  LC_xxx, LD_LIBRARY_PATH, LS_COLORS, TAPE, etc. Some of them
  are pretty close to a vulnerability, but they are in daily
  use, still.

- AFAICS coreutils' ls (as of 8.29) is not compatible to the
  "standard" ls anyway, already changing its behavior on the
  fly, unless (!) you define QUOTING_STYLE. Sample:

        % touch /tmp/a\ b
        % ls -1 /tmp/a\ b
        '/tmp/a b'
        % src/ls -1 /tmp/a\ b | cut -d\' -f1
        /tmp/a b
        % export QUOTING_STYLE=shell
        % src/ls -1 /tmp/a\ b | cut -d\' -f1

        %

When did pipes become unreliable?


Regards
Harri