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Re: Implement dash as bootstrap shell

On 08/12/15 08:55, Jonathan Perkin wrote:
* On 2015-12-07 at 19:01 GMT, Matthias Ferdinand wrote:


about a year ago I was using dash on my Ubuntu buildhosts, and after a
change in mk/wrapper/ the libtool builds stopped working
( )

Currently I just use WRAPPER_SHELL=/bin/bash, but dash is a lot

Looking at the current mk/wrapper/, it still uses the
problematic echo sequences \1 and \2:

     146                         $echo "s|\([$_sep]\)$1\(/[^$_sep]*\.la[$_sep]\)|\1$2\2|g"

which result in Ctrl-A and Ctrl-B under dash (also dash from pkgsrc).
This is a known issue.  The default dash behaviour (and that of the
Debian/Ubuntu implementation) is within its POSIX rights to implement
'echo \[0-9]' differently to other shells as the behaviour is
implementation defined.

However in my proposal I chose the pragmatic route and include the
Gentoo patch which changes the behaviour to what you'd expect, thus
avoiding any of these issues.

I've spent time in the past trying to come up with a reasonable way of making dash work, and gave up for the reason of this extremely unhelpful dash behaviour, and because pdksh does actually Just Work these days (after an integer overflow bug was fixed a while back).

I really don't see much benefit in having a patched version of dash that behaves differently to every other version of dash, since the very way it would behave differently is also such a point of contention with the dash maintainers for some reason (and therefore the patch will never make it into "standard dash").

That leaves us barely better off than using pdksh - which is comparably fast, and more likely to be available on other platforms as a base shell than a hacked dash will be (E.g. I can "apt-get install pdksh", but I can't "apt-get install dash-not-the-normal-dash-but-the-special-patched-dash").

How about making work with the standard dash behaviour instead - perhaps by using "printf" instead of "echo" in under dash?

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