NAME

stardate - convert between stardates and other calendars

SYNOPSIS

stardate [ options ] [ date ... ]

DESCRIPTION

stardate interprets the dates specified on its command line, and outputs them in the formats specified by the options.

If no dates are specified, the current time, read from the system clock, is used. If no options are specified, dates are output in the form of stardates. Consequently, if stardate is invoked with no arguments, it outputs the current time as a stardate. This performs much the same job as date(1), but with a more interesting form of output.

Dates on output are always rounded down, and so in some cases will generate different output if reused as input. This rounding is always such that the output date is the latest time, expressible in the format being used, that is no later than the time specified as input.

This program handles dates from 0001=01=01 (Julian calendar) up to (currently) (2^64 - 1) seconds later, which is beyond the year (5 x 10^11). Any date within this range can be input or output in any of the formats the program supports. Consequently, any date the program outputs will be accepted as input. The only exception is for dates within the first half second of the acceptable range, where the value output in the quadcent calendar, ``0000*12*31T02:03:16'' (chosen due to the rounding mentioned above), is actually outside the acceptable range.

The stardate code is based on information in version 1 of the Stardates in Star Trek FAQ, which is regularly posted to the USENET newsgroup rec.arts.startrek.tech.

OPTIONS

-s[n]: Output the date as a stardate. n, if given, specifies the number of digits output after the decimal point. If not specified, it defaults to 2. The output looks like ``[i]nnnn.dd''.

When 2 decimal places are used, the output of the current time changes every 172.8 seconds. (Actually, because of the resolution of C time, four-fifths of the changes are 173 seconds after the previous change, and the other fifth are 172 seconds after.)

-j: Output the date as a date in the Julian calendar, with UTC time. The output looks like ``yyyy=mm=ddThh:mm:ss''.
-g: Output the date as a date in the Gregorian calendar, with UTC time. The output looks like ``yyyy-mm-ddThh:mm:ss''.
-q: Output the date as a date in the Quadcent calendar, with UTC time. The output looks like ``yyyy*mm*ddThh:mm:ss''.

This calendar is explained in detail in the Stardates in Star Trek FAQ. Briefly, it uses seconds that are approximately 1.00066 SI seconds long, and has no leap years. Each 400 years in this calendar is exactly as long as 400 years in the Gregorian calendar, but all years in the quadcent calendar are the same length.

-u: Output the date in the form of the traditional Unix time. This is a number of seconds since midnight UTC on 1970-01-01. The output looks like ``Unnnnnnnnn''.
-x: Output the date in the form of the traditional Unix time, in hexadecimal. The output looks like ``U0xnnnnnnnnn''.

INPUT FORMATS

dates may be specified in any of the output formats, as described above, with a few variations allowed. More precisely, the following forms are permitted:

[issue]nnnn
[-issue]nnnn
[issue]nnnn.dd
[-issue]nnnn.dd: A stardate. The issue number, with the square brackets, is mandatory. The fractional part is optional.

Stardate ``[0]0000.0'' is midnight UTC on 2162-01-04; negative issue numbers indicate times before that. If issue is less than 20, the number must be in the range [0, 10000). If equal to 20, [0, 5006). If greater than 20, [0, 100000). The FAQ explains these range changes.

yyyy=mm=dd
yyyy=mm=ddThh:mm
yyyy=mm=ddThh:mm:ss: A date in the Julian calendar, optionally with a time in UTC.
yyyy-mm-dd
yyyy-mm-ddThh:mm
yyyy-mm-ddThh:mm:ss: A date in the Gregorian calendar, optionally with a time in UTC.
yyyy*mm*dd
yyyy*mm*ddThh:mm
yyyy*mm*ddThh:mm:ss: A date in the Quadcent calendar, optionally with a time in UTC.
Unnnnnnnnnn
U-nnnnnnnnnn
U0xnnnnnnnnnn
U-0xnnnnnnnnnn: A Unix time specification - a number of seconds since 1970-01-01. A negative number indicates a time before 1970. In the forms with ``0x'', the number is in hexadecimal.

Case of alphabetic characters in input is ignored.

AUTHOR

Andrew Main <zefram@fysh.org>

BUGS

This program will not handle dates BCE.