Hi Thorsten, On Wed, Jul 29, 2009 at 01:25:48PM +0000, Thorsten Glaser wrote: > Debian Policy 10.4 states that shell scripts using a /bin/sh shebang > line must conform to POSIX Shell, with a few (listed) exceptions.
> http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html > specifies, under “Command Search and Execution” 1.c, a list of required > shell builtins. I cannot find printf(1) there, or in any other place of > current SUSv3 (online edition), for that matter, except as stand-alone > utility. > udev uses /bin:/sbin as $PATH whereas printf(1) lies in /usr/bin. > udev uses printf nevertheless, assuming it right because GNU bash sup- > ports it and dash, unlike posh (I think) and other Debian Policy 10.4 > compliant /bin/sh-capable shells, implements it as a speed hack (lower > boot times combined with portable use of printf, since echo isn’t). > I call for the CTTE to decide that no maintainer is above Policy 10.4 > and that udev shall be fixed to not use printf as builtin, or require > a different shebang. You're aware that [ (test) is also not listed as a mandatory shell built-in, according to the POSIX reference you've cited? Yet the following list of scripts make use of it at boot time, prior to the point at which /usr is guaranteed to be mounted: /etc/rcS.d/S01readahead /etc/rcS.d/S02hostname.sh /etc/rcS.d/S02mountkernfs.sh /etc/rcS.d/S06keyboard-setup /etc/rcS.d/S07linux-restricted-modules-common /etc/rcS.d/S10udev /etc/rcS.d/S11mountdevsubfs.sh /etc/rcS.d/S13pcmciautils /etc/rcS.d/S15module-init-tools /etc/rcS.d/S17procps /etc/rcS.d/S20checkroot.sh /etc/rcS.d/S22mtab.sh /etc/rcS.d/S25brltty /etc/rcS.d/S26cryptdisks-early /etc/rcS.d/S28cryptdisks /etc/rcS.d/S30checkfs.sh /etc/rcS.d/S30etc-setserial /etc/rcS.d/S35mountall.sh 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 think using printf is okay *as long* as it it possible for the > script to pick it up in /usr/bin/ and *not* rely on an unportable > builtin. The whole point of Policy 10.4 is portability, and maybe > even portability beyond Debian. It _is_ well-known, after all, > that shell and utility "echo" are both unportable. (This serves > as comment to #490605.) 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. Does the mksh package somehow support switching /bin/sh automatically on installation? If not, I think the best option may be to document for users who want to use mksh instead of dash/bash that /usr must be on the same partition as /. >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. 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? -- Steve Langasek Give me a lever long enough and a Free OS Debian Developer to set it on, and I can move the world. Ubuntu Developer http://www.debian.org/ [email protected] [email protected] -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
