The format argument enables the user to pass custom formatting of date and time based on formatting codes from the C standard. The file formats are designed to be used to construct file names at CLI, such as $filename = (date format=fileDate) + ".log".
Pre-Defined format option: (Results may vary slightly depending on host locale)
custom Format codes from the C standard full Friday November 07, 2008 at 12:00:36.3467824 AM fullDate Friday November 07, 2008 fullTime 12:00:36.3467824 AM iso 2008-11-07T12:00:36 long November 07, 2008 at 12:00:36 AM longDate November 07, 2008 longTime 12:00:36 AM medium Nov 07, 2008, 12:00 AM mediumDate Nov 07, 2008 mediumTime 12:00:36 AM short 11/07/08, 12:00 AM shortDate 11/07/08 shortTime 12:00 AM date 2008-11-07 time 12:00:36 file 20081107_120036 fileDate 20081107 fileTime 120036