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

[Marco Atzeri]

On 30.03.2021 19:18, Brian Inglis wrote:
> 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
> 

it really depends on the history of the package,
I have tons of package with "0" that in reality were picked
long time ago.
So it is not 100% trustable on long time installation