Version number of the "cygwin" Cygwin package: ``` cygcheck -c cygwin ``` Version numbers of all installed Cygwin packages: ``` cygcheck -c ``` Save that information to a file: ``` cygcheck -c > cygwin-package-versions.txt ``` Save more complete information to a file: ``` cygcheck -s -r -v > cygcheck.out ```