How to uninstall packages that were installed as dependency but are no longer required

Brian Inglis
Tue Mar 30 17:18:32 GMT 2021

On 2021-03-30 02:07, Marco Atzeri via Cygwin wrote:
> On 30.03.2021 07:51, Yasuhiro Kimura wrote:
>> If you repeat the update of installed Cygwin packages for a while,
>> it's quite possible that there are some packages that were installed
>> as dependency but are no longer required by any others.
>> Then is there any way to detect and uninstall such ones?
>> I expect such way as `apt autoremove` of Debian or `dnf autoremove` of
>> Fedora.

> as currently we are not tracking between choosen packages
> and installed by dependency, Cygwin is lacking such capabilities

The undocumented third field in installed.db is automatic dependency 0 / 
manually picked 1:

$ sort -k3 /etc/setup/installed.db | uniq -cf2
          1 INSTALLED.DB 3
       1203 _autorebase _autorebase-001007-1.tar.bz2 0
        467 aalib aalib-1.4rc5-12.tar.bz2 1

> the most likely candidates for removal are the different version
> of the same libraries
> $ cygcheck -cd | grep "^lib" | tee lib.txt
> in my case I see
> libvpx1                                 1.3.0-2
> libvpx3                                 1.5.0-1
> libvpx4                                 1.6.1-1
> libvpx5                                 1.7.0-1
> $ cygcheck-dep -q -n libvpx1 libvpx3 libvpx4 libvpx5
> libvpx1: is needed for ( )
> libvpx3: is needed for ( )
> libvpx4: is needed for ( )
> libvpx5: is needed for ( gstreamer1.0-plugins-good libvpx-devel )

Using the above info you could run a check for automatic dependencies no longer 
needed, but you *MUST* retain and not attempt to deinstall Base packages, plus 
packages automatically installed to replace obsolete packages, which ideally 
would inherit the manually picked flag of the obsolete package.

Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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