windows equivalents for popular unix commands

Some Windows cmd equivalents for common Unix commands for my onw reference

unix	cmd	powershell
echo $variable	echo %variable%	$variable $Env:variable //environment variable
cp source target	copy source target
cp -r source target	xcopy source target /e/h
find -name '*.txt'	dir /s *.txt
grep text	findstr text
ls -a	dir /a
rm file	del file
rm -rf directory	rmdir /s /q directory
which command	where command