[Buildroot] shell issues when /bin/sh is 'dash' instead of 'bash'

[Buildroot] shell issues when /bin/sh is 'dash' instead of 'bash'

[Wade Berrier]

Hi,

There are a few Makefiles that rely on some bash specific code:

findutils
sed
tar
tftpd

(grep used to, but was fixed by Jacmet circa 6 months ago)

The culprit is the "-ot" operator.  From the advanced bash scripting guide:

[ FILE1 -ot FILE2 ]	True if FILE1 is older than FILE2, or is FILE2
exists and FILE1 does not.

'dash' doesn't follow the "or is FILE2 exists and FILE1 does not." portion.

The result is that some files don't get installed into the target
system when /bin/sh points to dash (like on recent ubuntu and debian?
distros)

Attached is a patch to use CONFIG_SHELL.

Question: is this the best way to fix this?  Or maybe these packages
should be fixed more in the style of how Jacmet fixed grep? (see
http://sources.uclibc.org/index.py/trunk/buildroot/package/grep/grep.mk?r1=22930&r2=22931
)

Feedback?

Wade
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[Buildroot] shell issues when /bin/sh is 'dash' instead of 'bash'

[Hamish Moffatt]

On Wed, Dec 31, 2008 at 04:04:37PM -0700, Wade Berrier wrote:
> The result is that some files don't get installed into the target
> system when /bin/sh points to dash (like on recent ubuntu and debian?
> distros)
> 
> Attached is a patch to use CONFIG_SHELL.

Why aren't we setting SHELL=$(CONFIG_SHELL) somewhere, rather than using
$(CONFIG_SHELL) explicitly in each place? (And why do I have the feeling
we've had this discussion before?)

> Question: is this the best way to fix this?  Or maybe these packages
> should be fixed more in the style of how Jacmet fixed grep? (see
> http://sources.uclibc.org/index.py/trunk/buildroot/package/grep/grep.mk?r1=22930&r2=22931
> )

dash(1) on my system says -ot is supported anyway. If not perhaps it can
be expressed in a better way; I think that would be better than this
fix.

Besides is CONFIG_SHELL guaranteed to be bash anyway?



Happy new year.

Hamish
-- 
Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>

[Buildroot] shell issues when /bin/sh is 'dash' instead of 'bash'

[Wade Berrier]

On Wed, Dec 31, 2008 at 7:36 PM, Hamish Moffatt <hamish@cloud.net.au> wrote:
> On Wed, Dec 31, 2008 at 04:04:37PM -0700, Wade Berrier wrote:
>> The result is that some files don't get installed into the target
>> system when /bin/sh points to dash (like on recent ubuntu and debian?
>> distros)
>>
>> Attached is a patch to use CONFIG_SHELL.
>
> Why aren't we setting SHELL=$(CONFIG_SHELL) somewhere, rather than using
> $(CONFIG_SHELL) explicitly in each place? (And why do I have the feeling
> we've had this discussion before?)

Yes, I think this has been discussed before...

>
>> Question: is this the best way to fix this?  Or maybe these packages
>> should be fixed more in the style of how Jacmet fixed grep? (see
>> http://sources.uclibc.org/index.py/trunk/buildroot/package/grep/grep.mk?r1=22930&r2=22931
>> )
>
> dash(1) on my system says -ot is supported anyway. If not perhaps it can
> be expressed in a better way; I think that would be better than this
> fix.

dash supports '-ot', but it doesn't have the same behavior as bash
when one of the files is missing.  I tend to agree... it could
probably be expressed in a better way.

>
> Besides is CONFIG_SHELL guaranteed to be bash anyway?

It will prefer bash, but will fall back on /bin/sh, which could be dash.

>
>
>
> Happy new year.

You too!

Wade

[Buildroot] shell issues when /bin/sh is 'dash' instead of 'bash'

[Peter Korsgaard]

>>>>> "Hamish" == Hamish Moffatt <hamish@cloud.net.au> writes:

 Hamish> On Wed, Dec 31, 2008 at 04:04:37PM -0700, Wade Berrier wrote:
 >> The result is that some files don't get installed into the target
 >> system when /bin/sh points to dash (like on recent ubuntu and debian?
 >> distros)
 >> 
 >> Attached is a patch to use CONFIG_SHELL.

 Hamish> Why aren't we setting SHELL=$(CONFIG_SHELL) somewhere, rather
 Hamish> than using $(CONFIG_SHELL) explicitly in each place? (And why
 Hamish> do I have the feeling we've had this discussion before?)

Because we already discussed it earlier ;) - Without any
conclusion. The CONFIG_SHELL afaik comes from the kconfig legacy, but
other projects like U-Boot have recently skipped it and simply set
SHELL.

I have done it as well for buildroot, and a test build seems to work
fine, so I'll commit it in a moment. We still need to set CONFIG_SHELL
though for the kconfig stuff (or fix their makefiles, but I would
prefer to keep the difference between us and upstream minimal).

 Hamish> Besides is CONFIG_SHELL guaranteed to be bash anyway?

No, it currently falls back to /bin/sh if bash isn't there. We should
probably add a check in dependencies.sh

 Hamish> Happy new year.

You too.

-- 
Bye, Peter Korsgaard

[Buildroot] shell issues when /bin/sh is 'dash' instead of 'bash'

[Nicolas Pitre]

On Thu, 1 Jan 2009, Hamish Moffatt wrote:

> On Wed, Dec 31, 2008 at 04:04:37PM -0700, Wade Berrier wrote:
> > The result is that some files don't get installed into the target
> > system when /bin/sh points to dash (like on recent ubuntu and debian?
> > distros)
> > 
> > Attached is a patch to use CONFIG_SHELL.
> 
> Why aren't we setting SHELL=$(CONFIG_SHELL) somewhere, rather than using
> $(CONFIG_SHELL) explicitly in each place? (And why do I have the feeling
> we've had this discussion before?)
> 
> > Question: is this the best way to fix this?  Or maybe these packages
> > should be fixed more in the style of how Jacmet fixed grep? (see
> > http://sources.uclibc.org/index.py/trunk/buildroot/package/grep/grep.mk?r1=22930&r2=22931
> > )
> 
> dash(1) on my system says -ot is supported anyway. If not perhaps it can
> be expressed in a better way; I think that would be better than this
> fix.

There are other places where brace expansion is used for arguments to 
patch-kernel.sh, and dash doesn't supports that.  You end up with a 
kernel missing appropriate patches, etc.


Nicolas

[Buildroot] shell issues when /bin/sh is 'dash' instead of 'bash'

[Peter Korsgaard]

>>>>> "Nicolas" == Nicolas Pitre <nico@cam.org> writes:

Hi,

 >> dash(1) on my system says -ot is supported anyway. If not perhaps it can
 >> be expressed in a better way; I think that would be better than this
 >> fix.

 Nicolas> There are other places where brace expansion is used for arguments to 
 Nicolas> patch-kernel.sh, and dash doesn't supports that.  You end up with a 
 Nicolas> kernel missing appropriate patches, etc.

Exactly. The best way forward is imho to always use bash like what
current svn is doing.

-- 
Bye, Peter Korsgaard