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Manual Reference Pages  -  DROUND (1)


dround - Round dates or times to designated values






dround 0.2.7

Round DATE/TIME to the next occurrence of RNDSPEC.

If DATE/TIME is omitted a stream of date/times is read from stdin.

DATE/TIME can also be one of the following specials
- ‘now’ interpreted as the current (UTC) time stamp
- ‘time’ the time part of the current (UTC) time stamp
- ‘today’
  the current date (according to UTC)
- ‘tomo[rrow]’
  tomorrow’s date (according to UTC)
- ‘y[ester]day’
  yesterday’s date (according to UTC)
RNDSPECs can be month names (Jan, Feb, ...), weekday names (Sun, Mon, ...), or days. If a month name the next date/time relative to DATE/TIME is returned whose month part matches the value given, so e.‘g. dround 2012-01-01 Feb’ will return 2012-02-01. If a weekday name is given, the next date/time after DATE/TIME whose weekday part matches the values given is returned. If a day, the next date/time after DATE/TIME whose day part matches is returned, so ‘dround 2012-01-15 1’ will return 2012-02-01.
RNDSPECs can also be multiples of the day dividing units, e.g 1h rounds to the nearest full hour, 30m to the nearest half hour, and 10s to the next 10s mark.
To round to the previous occurrence of a RNDSPEC any argument can be prefixed with a ‘-’ to denote that. E.g. ‘dround 2012-02-14 -1’ will return 2012-02-01. And ‘dround 2012-02-11 -- -Sep’ will return 2011-09-11.
Multiple RNDSPECs are evaluated left to right.
Note that rounding isn’t commutative, e.g.
2012-03-01 Sat Sep -> 2012-09-03
2012-03-01 Sep Sat -> 2012-09-01
Note that non-numeric strings prefixed with a ‘-’ conflict with the command line options and a separating ‘--’ has to be used.
-h, --help Print help and exit
-V, --version
  Print version and exit
-q, --quiet
  Suppress message about date/time and duration parser errors.
-f, --format=STRING
  Output format. This can either be a specifier string (similar to strftime()’s FMT) or the name of a calendar.
-i, --input-format=STRING
  Input format, can be used multiple times. Each date/time will be passed to the input format parsers in the order they are given, if a date/time can be read successfully with a given input format specifier string, that value will be used.
-e, --backslash-escapes
  Enable interpretation of backslash escapes in the output and input format specifier strings.
-S, --sed-mode
  Copy parts from the input before and after a matching date/time. Note that all occurrences of date/times within a line will be processed.
  Interpret dates on stdin or the command line as coming from the time zone ZONE.
-z, --zone=ZONE
  Convert dates printed on stdout to time zone ZONE, default: UTC.
-n, --next Always round to a different date or time.


$ dround 2012-03-01 2

$ dround -n 2012-03-01 1

$ dround 17:04:00 5m

$ dround -n 17:04:00 1m


Format specs in dateutils are similar to posix’ strftime().

However, due to a broader range of supported calendars dateutils must employ different rules.

Date specs:
%a The abbreviated weekday name
%A The full weekday name
%_a The weekday name shortened to a single character (MTWRFAS)
%b The abbreviated month name
%B The full month name
%_b The month name shortened to a single character (FGHJKMNQUVXZ)
%c The count of the weekday within the month (range 00 to 05)
%C The count of the weekday within the year (range 00 to 53)
%d The day of the month, 2 digits (range 00 to 31)
%D The day of the year, 3 digits (range 000 to 366)
%F Equivalent to %Y-%m-%d (ymd’s canonical format)
%j Equivalent to %D
%m The month in the current calendar (range 00 to 19)
%Q The quarter of the year (range Q1 to Q4)
%q The number of the quarter (range 01 to 04)
%s The number of seconds since the Epoch.
%u The weekday as number (range 01 to 07, Sunday being 07)
%U The week count, first day of week is Sun (range 00 to 53)
%V The ISO week count, first day of week is Mon (range 01 to 53)
%w The weekday as number (range 00 to 06, Sunday being 00)
%W The week count, first day of week is Mon (range 00 to 53)
%y The year without a century (range 00 to 99)
%Y The year including the century

%Od The day as roman numerals
%Om The month as roman numerals
%Oy The two digit year as roman numerals
%OY The year including the century as roman numerals

%rs In time systems whose Epoch is different from the unix Epoch, this
selects the number of seconds since then.
%rY In calendars with years that don’t coincide with the Gregorian
years, this selects the calendar’s year.

%dth The day of the month as an ordinal number, 1st, 2nd, 3rd, etc.
%mth The month of the year as an ordinal number, 1st, 2nd, 3rd, etc.

%db The business day of the month (since last month’s ultimo)
%dB Number of business days until this month’s ultimo

Time specs:
%H The hour of the day using a 24h clock, 2 digits (range 00 to 23)
%I The hour of the day using a 12h clock, 2 digits (range 01 to 12)
%M The minute (range 00 to 59)
%N The nanoseconds (range 000000000 to 999999999)
%p The string AM or PM, noon is PM and midnight is AM.
%P Like %p but in lowercase
%S The second (range 00 to 60, 60 is for leap seconds)
%T Equivalent to %H:%M:%S

General specs:
%n A newline character
%t A tab character
%% A literal % character

%O Modifier to turn decimal numbers into Roman numerals
%r Modifier to turn units into real units
th Suffix, read and print ordinal numbers
b Suffix, treat days as business days

By design dates before 1601-01-01 are not supported.

For conformity here is a list of calendar spec names and their meaning:
ymd %Y-%m-%d
ymcw %Y-%m-%c-%w
ywd %rY-W%V-%u
bizda %Y-%m-%db


Some tools ("dadd", "dseq") need durations as their input. Durations are generally incompatible with input formats as specified by "-i|--input-format" and (at the moment) the input syntax is fixed.

The general format is "[+-]Nunit" where "+" or "-" is the sign, "N" a number, and "unit" the unit as discussed below.

s seconds
m minutes
h hours
rs real-life seconds, as in including leap second transitions

d days
b business days
mo months
y years


Written by Sebastian Freundt <>


Report bugs to:


The full documentation for dround is maintained as a Texinfo manual. If the info and dround programs are properly installed at your site, the command
info (dateutils)dround
should give you access to the complete manual.
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dateutils 0.2.7 DROUND (1) January 2014

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