ruby_time_cheat_sheet.rb

#Date Formatting I
'%Y' #Year with century (e.g. 2015, 1995, etc)
'%m' #Month of the year, zero-padded (01..12)
'%B' #The full month name (e.g. January)
'%b' #The abbreviated month name (e.g. Jan)
'%d' #Day of the month, zero-padded (01..31)
'%j' #Day of the year (001..366)


#Flags I
'-' #Don't pad a numerical output
'_' #Use spaced for padding
'0' #Use zeros for padding
'^' #Upcase the result string
'#' #Change case
':' #Use colons for %z 


#Date Formatting II
'%C'  #Year / 100 (round down. e.g. 20 in 2015)
'%y'  #Year % 100 (00...99)
'%_m' #Month of the year, blank-padded (_1..12)
'%-m' #Month of the year, no-padding (1..12)
'%^B' #The full month name uppercased (e.g. JANUARY)
'%^b' #The abbreviated month name uppercased (e.g. JAN)
'%h'  #Equivalent to %b (abbreviated month name)
'%-d' #Day of the month, no-padding (1..31)
'%e' #Day of the month, blank-padded (_1..31)