Do you want to show the time a file was modified instead of the date? Excerpt from the man page of ls
If the time of last modification is greater than six months ago, it is shown in the format `month date year' for the POSIX locale. When the LC_TIME locale category is not set to the POSIX locale, a different format of the time field may be used. Files modified within six months show `month date time'.
As for a simple one liner, I can give you a simple two liner:
#!/usr/bin/perl -w #-d
$mtime=(stat($ARGV)); @ltime=localtime $mtime; printf "%.4d-%.2d-%.2d-%.2d-%.2d\n",$ltime+1900,$ltime+1,$ltime,$ltime,$ltime;