Mailing List Archive: My N900 has diffmo as an essential package; safe to remove?

My N900 has diffmo as an essential package; safe to remove?

Jan 13, 2011, 4:30 PM

Post #1 of 4 (1749 views)

Hi Maemo users,

I wanted to install diffutils-gnu on my N900, but it seems to conflict
with diffmo, and diffmo seems to be "essential". I'm not a Debian guy
and am not entirely familiar with how the apt-stuff works and why this
package is essential. As far as I can tell, no other (installed)
packages depend on it, but I may not be looking it up properly. I
don't remember installing it but it's entirely possible that I did one
day and just don't remember.

So I suppose I have two questions:
1) What causes a package to become "essential"?
2) Is it actually safe to remove diffmo? I don't want an unbootable
device or anything bad like that.

Thanks.

Some apt-output is below:

Nokia-N900:~# apt-get -s install diffutils-gnu
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
diffmo
The following NEW packages will be installed:
diffutils-gnu
WARNING: The following essential packages will be removed.
This should NOT be done unless you know exactly what you are doing!
diffmo
0 upgraded, 1 newly installed, 1 to remove and 2 not upgraded.
Remv diffmo [1:2.8.1-21]
Inst diffutils-gnu (1:2.8.1-18maemo3 Extras:2.0/fremantle-1.3,
Extras-devel:2.0/fremantle, Extras-testing:2.0/fremantle)
Conf diffutils-gnu (1:2.8.1-18maemo3 Extras:2.0/fremantle-1.3,
Extras-devel:2.0/fremantle, Extras-testing:2.0/fremantle)

Nokia-N900:~# apt-cache rdepends diffmo
diffmo
Reverse Depends:
colordiffmo
diffutils-gnu

Nokia-N900:~# apt-get remove colordiffmo diffutils-gnu
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package colordiffmo is not installed, so not removed
Package diffutils-gnu is not installed, so not removed
0 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.
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Re: My N900 has diffmo as an essential package; safe to remove? [ In reply to ]

marius.vollmer at nokia

Jan 13, 2011, 11:41 PM

Post #2 of 4 (1715 views)

Permalink

ext Paul Hartman <paul.hartman+maemo@gmail.com> writes:

> So I suppose I have two questions:
> 1) What causes a package to become "essential"?

The maintainer of that package has decided to make it essential and puts
a "Essential: yes" field into debian/control.

For Maemo, packages often become "essential" by accident when packaging
bits are copied over from Debian.

> 2) Is it actually safe to remove diffmo? I don't want an unbootable
> device or anything bad like that.

I assume that diffmo is a replacement for busybox /bin/diff. If so,
then you only need to make sure that you always have a working
/bin/diff. Thus, if after removing diffmo you end up without /bin/diff,
repair that immediately, maybe by symlinking it to busybox, or by
installing diffutils-gnu.

(If this is not about /bin/diff, then I apologize for the confusion.)
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Re: My N900 has diffmo as an essential package; safe to remove? [ In reply to ]

eero.tamminen at nokia

Jan 14, 2011, 6:42 AM

Post #3 of 4 (1690 views)

Permalink

Hi,

ext Marius Vollmer wrote:
> ext Paul Hartman <paul.hartman+maemo@gmail.com> writes:
>
>> So I suppose I have two questions:
>> 1) What causes a package to become "essential"?
>
> The maintainer of that package has decided to make it essential and puts
> a "Essential: yes" field into debian/control.
>
> For Maemo, packages often become "essential" by accident when packaging
> bits are copied over from Debian.

Yes, "diff" is essential in Debian.

It's not an essential in Maemo.

>> 2) Is it actually safe to remove diffmo? I don't want an unbootable
>> device or anything bad like that.
>
> I assume that diffmo is a replacement for busybox /bin/diff. If so,
> then you only need to make sure that you always have a working
> /bin/diff. Thus, if after removing diffmo you end up without /bin/diff,
> repair that immediately, maybe by symlinking it to busybox, or by
> installing diffutils-gnu.

Default Busybox isn't built with "diff" utility (diff version in
Fremantle Busybox is too incompatible with real diff), so symlink
to that would be wrong.

If no package is depending on "diffmo", I think it's safe just to
remove it.

> (If this is not about /bin/diff, then I apologize for the confusion.)

- Eero
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Re: My N900 has diffmo as an essential package; safe to remove? [ In reply to ]

paul.hartman+maemo at gmail

Jan 14, 2011, 8:37 AM

Post #4 of 4 (1715 views)

Permalink

On Fri, Jan 14, 2011 at 8:42 AM, Eero Tamminen <eero.tamminen@nokia.com> wrote:
> Hi,
>
> ext Marius Vollmer wrote:
>>
>> ext Paul Hartman <paul.hartman+maemo@gmail.com> writes:
>>
>>> So I suppose I have two questions:
>>> 1) What causes a package to become "essential"?
>>
>> The maintainer of that package has decided to make it essential and puts
>> a "Essential: yes" field into debian/control.
>>
>> For Maemo, packages often become "essential" by accident when packaging
>> bits are copied over from Debian.
>
> Yes, "diff" is essential in Debian.
>
> It's not an essential in Maemo.
>
>
>>> 2) Is it actually safe to remove diffmo? I don't want an unbootable
>>> device or anything bad like that.
>>
>> I assume that diffmo is a replacement for busybox /bin/diff. If so,
>> then you only need to make sure that you always have a working
>> /bin/diff. Thus, if after removing diffmo you end up without /bin/diff,
>> repair that immediately, maybe by symlinking it to busybox, or by
>> installing diffutils-gnu.
>
> Default Busybox isn't built with "diff" utility (diff version in
> Fremantle Busybox is too incompatible with real diff), so symlink
> to that would be wrong.
>
> If no package is depending on "diffmo", I think it's safe just to
> remove it.

Thanks Marius and Eero for your quick replies and good information.

In fact, like Eero says, I did not have "diff" at all, symlink or
otherwise. (That's why I was installing diffutils-gnu, and probably
why I installed diffmo at some time in the past)

I have safely removed diffmo and installed diffutils-gnu, with
prefixed /usr/bin/gnu on my shell path and everything seems to work.

Thanks again!
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