Bug#539158: […] assumes printf is a builtin
Steve Langasek dixit:
>You're aware that [ (test) is also not listed as a mandatory shell built-in,
>according to the POSIX reference you've cited?
Interesting.
>So from that perspective, there are lots of POSIX failures. Do you think we
>should treat [ specially, but not printf, because mksh happens to implement
>the one as a built-in but not the other?
I see that this weakens my argumentation, but I could still mention
that [ lies in /bin/ on BSD (and possibly a lot more OSes), and that
(almost?) all POSIX compatible shells available on Debian implement
it, whereas having printf as builtin is a feature in GNU bash, a mere
speed hack in dash, and not available in many other shells.
>No, portability beyond Debian is not relevant to Policy 10.4. We've never
>been able to usefully rely on /bin/sh complying with POSIX on arbitrary
>other Unices.
I didn’t mean that; it was more in the sense of writing somewhat portable
POSIX (not Bourne) shell scripts.
>Does the mksh package somehow support switching /bin/sh automatically on
>installation?
Yes.
>who want to use mksh instead of dash/bash that /usr must be on the same
>partition as /.
udev EXPLICITLY sets $PATH to /bin:/sbin in its init script, so that is
not an option, unfortunately.
>>From a Policy perspective, it would be ideal to document the set of
>built-ins that we expect from a shell as /bin/sh, that scripts may rely on
>prior to the mounting of /usr.
Indeed. (Note that the printf in NetBSD® ash speed hack is rather recent.)
>Have you looked at this set yet, by chance,
>to see if there are others besides printf that mksh doesn't share with dash
>and bash?
Not yet, but I will and report.
I also have looked at adding a printf builtin to mksh, but I don’t quite
like it because it pulls in a *lot* of external symbols, including strtod,
and introduces floating point into the binary. This is undesirable (also
seeing that I have a project of an mksh linked against klibc, which I’d
like to offer for initramfs, replacing the one from klibc-utils *and*
busybox (if replacing both, at an actual size gain), for very little (in
terms of disc space) cost but some benefit).
bye,
//mirabilos
--
“It is inappropriate to require that a time represented as
seconds since the Epoch precisely represent the number of
seconds between the referenced time and the Epoch.”
-- IEEE Std 1003.1b-1993 (POSIX) Section B.2.2.2
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