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Re: Why two separate option namespaces?

From: Stephane Chazelas
Subject: Re: Why two separate option namespaces?
Date: Tue, 28 Feb 2017 17:14:41 +0000
User-agent: Mutt/1.5.24 (2015-08-30)

2017-02-27 16:18:46 -0500, Chet Ramey:
> On 2/27/17 11:50 AM, Martijn Dekker wrote:
> > So basically you're saying that, for options without a single-letter
> > equivalent, "-o" options are those that are either POSIX or that you
> > think should be POSIX? But then that distinction is more political than
> > technical, isn't it?
> Heh. Let's just say that I'm leaving the `set -o' namespace to Posix.

Well, not really since bash already has extensions over the
POSIX ones.

Note that all of ksh, yash and zsh at least have extensions of
their own there.

bash seems to be the last actively maintained POSIX-certified
shell, so I don't expect POSIX would come up with option names
that would conflict with bash's, so from that point of view, it
would be safe to merge the name spaces.

It may be worth checking other shell implementations to see if
there are potential conflicts. Uniformizing between all shells
would help writing scripts portable across several of the modern
Bourne-like shells.

zsh and yash are being conciliatory there in that they ignore
case, underscore (even hyphen for yash) and treat a "no" prefix
as inverting the setting.

yash and zsh also accept --<option> to "set" and to the
interpreter (in the case of yash, a la GNU, that is accepting
unambiguous abbreviations like set --posix for set

bash also accepts --<option> (but does not support GNU-like
abbreviations) for a restricted set of options like
verbose/posix. See also bash --restricted vs bash -O
restricted_shell (the latter one being ineffective).
(that's another set of "options" that may be worth merging).

So bash's shopt -s nocasematch also works as set -o nocasematch
in those shells (in addition to set +o CASE_MATCH for instance).
and bash's set -o posix also works (though with different
effect even if the intention is the same) in zsh and yash (even
if posix is not a valid option name in yash).

There are things like bash.extglob vs zsh.kshglob (zsh also has
zsh.extendedglob for its own extended globs)


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