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new 0.6.2 | Dec 19, 2024 |
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0.6.1 | Dec 19, 2024 |
0.6.0 |
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#245 in Date and time
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The julian-cli
package provides a julian
command for converting between
Julian day numbers and dates in the Gregorian calendar (either
proleptic or with the Reformation occurring at a given date) and/or the
proleptic Julian calendar. It is built on top of the
julian
library package by the same author.
Installation
In order to install the julian
command, you first need to have Rust and
Cargo installed. You can then build
the latest release of julian-cli
and install it in ~/.cargo/bin
by running:
cargo install julian-cli
Usage
julian [<options>] [<date> ...]
When invoked without arguments, the julian
command displays the current date
in the proleptic Gregorian calendar & UTC timezone along with the corresponding
Julian day number.
When julian
is invoked with one or more arguments, any calendar date
arguments (in the form "YYYY-MM-DD" or "YYYY-JJJ") are converted to Julian day
numbers, and any integer arguments are treated as Julian day numbers and
converted to calendar dates. By default, dates are read & written using the
proleptic Gregorian calendar, but this can be changed with the --julian
or
--reformation
option.
julian
uses astronomical year numbering, where 1 BC (the year
immediately before AD 1) is denoted on input & output as year 0 (displayed as
"0000"), and the year before that (normally called 2 BC) is denoted -1
(displayed as "-0001"). In addition, the start of the year is always taken as
being on January 1, even though not all users of the Julian calendar
throughout history have followed this convention.
Options
-
-c
,--countries
— List the country codes recognized by the-r
/--reformation
option. The output is a table with the following columns:- "Code" — the two-letter country code accepted by
--reformation
- "Country" — the country's English name (or a common variation thereof)
- "Reformation" — the Julian day number of the date on which the country first observed the Gregorian calendar
- "Last Julian" — the Old Style calendar date of the day before the reformation
- "First Gregorian" — the New Style calendar date of the day of the reformation
The database of country reformations dates is drawn from the Debian version of
ncal.c
as of 2023-04-26, so blame Debian for any historical inaccuracies. - "Code" — the two-letter country code accepted by
-
-h
,--help
— Display a summary of the command-line options and exit -
-j
,--julian
— Read & write dates using the proleptic Julian calendar -
-J
,--json
— Output JSON. See JSON Output below for more information. -
-o
,--ordinal
— Output calendar dates in the form "YYYY-JJJ", where the part after the hyphen is the day of the year from 001 to 366 (the ordinal date) -
-q
,--quiet
— Do not print the input value before each output value. Do not print "JDN" before Julian day numbers. -
-r <jdn>
,--reformation <jdn>
— Read & write dates using a reforming calendar in which the Gregorian calendar is first observed on the date with the given Julian day number.A two-letter country code (case insensitive) may be given in place of a JDN in order to use the calendar reformation as it was observed in that country. Run
julian --countries
to get a list of recognized country codes and their corresponding dates. -
-s
,--style
— Mark dates in reforming calendars as "O.S." (Old Style) or "N.S." (New Style)". Has no effect when-r
/--reformation
is not given or when-o
/--ordinal
is given. -
-V
,--version
— Show the program version and exit
JSON Output
When julian
is invoked with the -J
/--json
option, it outputs a JSON
breakdown of the chosen calendar and input & output values. The output
structure is an object with two keys, "calendar"
and "dates"
.
-
"calendar"
— Denotes the type of calendar selected for thejulian
invocation. This is an object that always contains at least one key,"type"
, the value of which is"gregorian"
(for the default proleptic Gregorian calendar),"julian"
(for the proleptic Julian calendar), or"reforming"
(for a reforming calendar). When"type"
is"reforming"
, there will be an additional field,"reformation"
, whose value is the Julian day number of the date on which the calendar first follows the Gregorian calendar. -
"dates"
— A list of objects, one per argument (or, if no arguments were given, one object for the current date). Each object contains the following fields describing the date indicated by the argument, regardless of whether the argument was a calendar date or a Julian day number:"julian_day_number"
— the date's Julian day number"year"
— the date's year"month"
— the number (1-12) of the date's month"day"
— the date's day-of-month (1-31)"ordinal"
— the date's one-based day-of-year ordinal (1-366)"display"
— the date in "YYYY-MM-DD" form"ordinal_display"
— the date in "YYYY-JJJ" form"old_style"
— This field is only present if the calendar in use is a reforming calendar. It istrue
if the date occurs before the calendar reformation,false
otherwise.
Dependencies
~325–770KB
~17K SLoC