How to add a repository using apt-cyg
You can run apt-cyg with the -m option to specify a mirror/repository. So this is what I did to install PHP from the Cygwinports repo.
apt-cyg update -m ftp://ftp.cygwinports.org/pub/cygwinports
Then I was able to install the packages from that repo.
apt-cyg install php
Modern interface for apt-cyg
from https://github.com/transcode-open/apt-cyg is:
$ apt-cyg mirror ftp://ftp.cygwinports.org/pub/cygwinports
$ apt-cyg update
$ apt-cyg install php
Repo with last WinXP support:
$ apt-cyg mirror ftp://www.fruitbat.org/pub/cygwin/circa/2016/08/30/104223
Official main repo:
$ apt-cyg mirror http://mirrors.kernel.org/sources.redhat.com/cygwin/
Multi sources support request on project github.
UPDATE As development under transcode-open
is stalled since 2016 use updating heir: https://github.com/kou1okada/apt-cyg