I am using cygwin on Windows 10. I can't seem to find any package named xv while in the cygwin setup. How can I use xv on Windows using cygwin or otherwise.
As XV is not provided you can try to compile it by yourself.
However as the code is a bit old, last version in 1994,
there is no guarantee that it will easily build in modern
systems like current Cygwin
As there are several equivalent programs in cygwin, you can try one of them.
I had installed XV on an older version of Cygwin-X like 5 years ago and xv would not come up on the startx windows. I would have to run the rxvt-native, and only then it would come up. On a newer computer with Windows 10, I installed Cygwin-X, but the rxvt-native is not available anymore (or not yet?) in the latest version of Cygwin-X. I wasn't able to have xv windows open up. So it seems, for now, xv can't work on Cygwin-X, at least not as it is. XV can still be obtained from John Bradley (just google xv john bradley) for a little fee and it will work on other unix-like OS, maybe with some tweaking because, as it has been mentioned, the software was written 24 years ago.