sorry for the delay,

On 2023/08/20 16:17:22 -0600, Todd C. Miller <millert@openbsd.org> wrote:
> Are there systems where program_invocation_short_name is available
> but __progname is not?  As far as I know, glibc on Linux also defines
> __progname.  Is there a reason to prefer program_invocation_short_name
> over __progname?

many of these compat/ files are often copied between -portable
projects, so it's hard to say.  I just checked both musl and glibc and
they have both program_invocation_short_name and __progname.  maybe a
very old version didn't have __progname?

maybe program_invocation_short_name was used since it's more
advertised on the GNU documentation?  (I can't find a manpage for
__progname while they have one for program_invocation_short_name.)