What is the Windows analog of the Linux watch command?

I’m looking for a Windows program/script/command line function that works like Linux’s watch program.

watch periodically calls another program/whatever and shows the result, which is great for refreshing an output file or similar every second:

watch cat my-output.txt

or, more powerfully:

watch grep "fail" my-output.txt

I’ve looked for it in cygwin’s library, but it doesn’t seem to be present.

Solution:

watch is available in Cygwin, in the procps package as listed here (this info can be found via the package search on the website, here). I don’t think this package is installed by the default cygwin setup, but it is one I usually select on new installs in order to have the watch command available.

The location of tools in packages usually match package names in Linux distributions (the package containing watch is procps on Debian and Ubuntu too) so if the Cygwin package search function fails you, info for/from Linux distributions may offer clues.