Re: sort - specifying sort fields/keys.

[Bob Proulx]

cga2000 wrote:
> Bob Proulx wrote:
> > You shouldn't ever need --color=never there unless you have aliased ls
> > with ls --color=always.  You don't want ls --color=always (really you
> > don't) and therefore you won't need to undo it with --color=never.
> 
> You're absolutely right. 
> 
> In fact I didn't want to have to worry about the effects of color escape
> codes on sort field counting at that point and that's why I initially
> specified --color=never.

It was pointed out to me in an offlist comment that sometimes people
*do want* ls --color=always.  Such as when forcing it and piping it
into less with 'ls --color=always | less -R'.  (Oh, I guess, yes. :-)

> On my system "ls" is aliased to "ls --color=auto".
> 
> Regrettably the man page provided on my system lists the three options
> (never, always, auto) but does not give any explanation as to what they
> actually do.

The man pages are great for quick reference of major features.  But
the primary documentation for most GNU software is in the info pages.

  info coreutils 'ls invocation'

  `--color [=WHEN]'
       Specify whether to use color for distinguishing file types.  WHEN
       may be omitted, or one of:
          * none - Do not use color at all.  This is the default.
          * auto - Only use color if standard output is a terminal.
          * always - Always use color.
       Specifying `--color' and no WHEN is equivalent to `--color=always'.
       Piping a colorized listing through a pager like `more' or `less'
       usually produces unreadable results.  However, using `more -f'
       does seem to work.

> I did a 
> 
> $ ls -al | sort -k1.1,1.1r -k8f
> 
> and the output is identical (properly sorted with dots ignored)

Based upon locale setting, right?

> >   
> > http://www.gnu.org/software/coreutils/faq/#Sort-does-not-sort-in-normal-order_0021
> 
> Thanks.  Good doc.

The descriptions usually talk about LC_ALL because it gets
complicated.  Really it is intended to set LANG.  But LANG is
overridden by LC_COLLATE and so setting LANG may have no effect.  But
LC_COLLATE is again overridden by LC_ALL.  Saying all of that in the
quick docs gets complicated and still doesn't really describe things
like how it interacts with LC_CTYPE.  I have no idea what (possibly
bad) effects there will be for setting an incompatible combination of
LANG, LC_CTYPE and LC_COLLATE will have on some languages.  So it
simpler just to describe LC_ALL=C as the biggest possible lever.  But
normally one would only set the lower priority locale vars such as
LANG and possibly LC_COLLATE such as I have done.

> > Apparently the people who defined the collating sequence for the en_*
> > locales confused working with data on a computer with working with
> > text on a computer.  The locale collating sequences for en_* ignores
> > punctuation and folds case by default!
> 
> Given the symptoms and the nature of sort I would probably never have
> figured that out myself. That there may be circumstances where this
> comes in handy I do not doubt .. But as to making it the default for one
> of (if not the) most widely-used locales?

It certainly annoys me.  But they didn't consult me when the collating
sequence was chosen.

> I gave  up on UTF-8 because I use mostly ELinks for browsing and afaik
> it's not UTF-8 ready.

How does ELinks compare to Links, Lynx, or w3m for UTF-8 support?  I
only use them for basic plain text us-ascii pages and so can't judge.

> I tested with LC_ALL=POSIX (as recommended in your document) and the
> "." was still being ignored.

Hmm...  Works for me.  Please double check everything.

  $ touch .baz .foo bar baz foa foo foz

  $ LC_ALL=en_US.UTF-8 ls -A1
  bar
  baz
  .baz
  foa
  foo
  .foo
  foz

  $ LC_ALL=C ls -A1
  .baz
  .foo
  bar
  baz
  foa
  foo
  foz

> So I issued the above export commands and (magically) data was sorted
> as data .. 

Oh good.

> Thank you very much for your clarification. 

Glad to help,
Bob