Ruby 1.8.7
%a - The abbreviated weekday name (“Sun”)
%A - The full weekday name (“Sunday”)
%b - The abbreviated month name (“Jan”)
%B - The full month name (“January”)
%c - The preferred local date and time representation
%d - Day of the month (01..31)
%H - Hour of the day, 24-hour clock (00..23)
%I - Hour of the day, 12-hour clock (01..12)
%l - Hour of the day, 12-hour clock without leading zero (1..12)
%j - Day of the year (001..366)
%m - Month of the year (01..12)
%M - Minute of the hour (00..59)
%p - Meridian indicator (“AM” or “PM”)
%S - Second of the minute (00..60)
%U - Week number of the current year,
starting with the first Sunday as the first
day of the first week (00..53)
%W - Week number of the current year,
starting with the first Monday as the first
day of the first week (00..53)
%w - Day of the week (Sunday is 0, 0..6)
%x - Preferred representation for the date alone, no time
%X - Preferred representation for the time alone, no date
%y - Year without a century (00..99)
%Y - Year with century
%Z - Time zone name
%% - Literal “%” character
t = Time.now
t.strftime("Printed on %m/%d/%Y") #=> "Printed on 04/09/2003"
t.strftime("at %I:%M%p") #=> "at 08:56AM"
Ruby 1.9
%a - The abbreviated weekday name (“Sun”)
%A - The full weekday name (“Sunday”)
%b - The abbreviated month name (“Jan”)
%B - The full month name (“January”)
%c - The preferred local date and time representation
%d - Day of the month (01..31)
%e - Day of the month,
a single digit is preceded by a space (range ' 1' to '31')
%F - Equivalent to %Y-%m-%d (the ISO 8601 date format)
%H - Hour of the day, 24-hour clock (00..23)
%I - Hour of the day, 12-hour clock (01..12)
%j - Day of the year (001..366)
%L - Millisecond of the second (000..999)
%m - Month of the year (01..12)
%M - Minute of the hour (00..59)
%N - Fractional seconds digits, default is 9 digits (nanosecond)
%3N millisecond (3 digits)
%6N microsecond (6 digits)
%9N nanosecond (9 digits)
%12N picosecond (12 digits)
%p - Meridian indicator (“AM” or “PM”)
%P - Meridian indicator (“am” or “pm”)
%s - Number of seconds since 1970-01-01 00:00:00 UTC.
%S - Second of the minute (00..60)
%U - Week number of the current year,
starting with the first Sunday as the first
day of the first week (00..53)
%W - Week number of the current year,
starting with the first Monday as the first
day of the first week (00..53)
%w - Day of the week (Sunday is 0, 0..6)
%x - Preferred representation for the date alone, no time
%X - Preferred representation for the time alone, no date
%y - Year without a century (00..99)
%Y - Year with century
%z - Time zone offset from UTC (+/-0000, e.g. EST = -0500)
%Z - Time zone name
%% - Literal “%” character
t = Time.now #=> 2007-11-19 08:37:48 -0600
t.strftime("Printed on %m/%d/%Y") #=> "Printed on 11/19/2007"
t.strftime("at %I:%M%p") #=> "at 08:37AM"
Controlling leading padding in Ruby 1.9
These codes work with any format code. %I is used as an example.
%-I - remove any leading zeroes or spaces (“1”)
%_I - force a leading space (and no leading zeroes) if necessary (“ 1”)
%0I - force a leading zero (and no leading spaces) if necessary (“01”)