You should find
dos2unix in the category Utils, Base, or Text. It’s easiest to use the search function.
If the package is not listed at all, try to use a different mirror.
If you installed this package while your cygwin terminal is still open, do a
rehash (depends on you shell) or simply start a new terminal.
Additional option, may be helpful for someone:
To install additional packages in windows from command line you can use your cygwin installer (which you’ve downloaded to install cygwin, it’s gui and all the stuff):
$ setup-x86_64.exe -q -P dos2unix
see this guide for details:
apt-cyg install dos2unix if you are in the cygwin Terminal
I had a similar problem that was due to me being extra stupid. In my case, I have both 32 and 64 bits builds of Cygwin installed. I had installed “dos2unix” on the 32 bit version, but not installed it on the 64 bit version. I couldn’t understand why the installer seemed to work, but I still couldn’t run it!
Advice – don’t install both versions of Cygwin. 🙂