Date format in powershell
Simple!
get-date -f "yyyy-MM-dd HH:mm:ss"
or...
(get-date).ToString("yyyy-MM-dd")
or better (worse) yet
[system.string]::format("{0:yyyy-mm-dd}", (get-date))
Formatting a list of dates...
dir *.txt | % { $_.LastWriteTime.ToString("yyyy-MM-dd") }