[tex-live] More on multiple minuses

[Heiko Oberdiek]

On Fri, Sep 05, 2008 at 01:16:46PM +0200, Martin Schröder wrote:

> 2008/9/5 Philip TAYLOR <P.Taylor at rhul.ac.uk>:
> >        > tlmgr ---help
> >
> > the first three of which appeared to generate
> > the same output, and the fourth of which
> > diagnosed an error.  Is there any difference
> 
> man 1 bash
>        --        A -- signals the end of options and disables further
> option processing.  Any arguments after
>                  the -- are treated as filenames and arguments.  An
> argument of - is equivalent to --.

tlmgr isn't bash and bash doesn't process options for other
programs. It's the task of the program which kind of syntax
it uses for its options.

Also '---help' isn't '--', the marker '--' is an argument of its own.
Thus some white space is needed to separate the marker from the
following stuff.

However tlmgr uses Getopt::Long:
| use Getopt::Long qw(:config no_autoabbrev require_order);

This perl package supports the convention, that an argument '--'
stops option processing of GetOptions.

The settings 'no_autoabbrev' and 'require_order' mean:

| auto_abbrev Allow option names to be abbreviated to
|             uniqueness.  Default is enabled unless envi­
|             ronment variable POSIXLY_CORRECT has been set,
|             in which case "auto_abbrev" is disabled.

| require_order
|             Whether command line arguments are allowed to
|             be mixed with options.  Default is disabled
|             unless environment variable POSIXLY_CORRECT
|             has been set, in which case "require_order" is
|             enabled.

'-help' works, because the feature "bundling" is not enabled.
"bundling" means, that short one-character options may be
merged together, e.g. "-h -e" could be given as "-he".
The price, long options must then be preceded by '--' to avoid
ambiguity.

Yours sincerely
  Heiko <oberdiek at uni-freiburg.de>