On Tue, Mar 29, 2022 at 2:37 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
> > On Tue, Mar 29, 2022 at 2:17 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> >> it's some random algorithm that they probably feel at liberty
> >> to change.
>
> > I guess that characterization surprises me. The man page for
> > getopt_long() says this, and has for a long time at least on systems
> > I've used:
>
> Yeah, they say they follow the POSIX spec when you set POSIXLY_CORRECT.
> What they don't spell out in any detail is what they do when you don't.
> We know that it involves rearranging the argv[] array behind the
> application's back, but not what the rules are for doing that. In
> particular, they must have some undocumented and probably not very safe
> method for deciding which arguments are neither switches nor switch
> arguments.
I mean, I think of an option as something that starts with '-'. The
documentation contains a caveat that says: "The special argument ‘--’
forces in all cases the end of option scanning." So I think I would
expect it just looks for arguments starting with '-' that do not
follow an argument that is exactly "--".
<looks around for the source code>
https://github.com/gcc-mirror/gcc/blob/master/libiberty/getopt.c
If an element of ARGV starts with '-', and is not exactly "-" or "--",
then it is an option element. The characters of this element
(aside from the initial '-') are option characters. If `getopt'
is called repeatedly, it returns successively each of the option characters
from each of the option elements.
OK - so I was off slightly. Either "-" or "--" terminates the options
list. Apart from that anything starting with "-" is an option.
I think you're overestimating the level of mystery that's present
here, as well as the likelihood that the rules could ever be changed.
--
Robert Haas
EDB: http://www.enterprisedb.com
