JDAY(1)

📦 version 2.4, in fedora 43, fedora 44

💖 JDAY 💖

okay bestie, pull up a chair, because we're talking about jday — that's the manual page from the JDAY(1) family, sitting pretty at version 2.4 ✨. Two little command line cuties, jday and j2d, who do the exact same job in opposite directions. Slay.

✨ NAME ✨

jday, j2d — astronomical julian date conversion utilities 🪐

🌸 SYNOPSIS 🌸

jday

jday [-d [-]year-mm-dd hh:mm:ss]

jday [--version]

jday [--h[elp]]

j2d <julian decimal date>

j2d [--version]

j2d [--h[elp]]

🦋 DESCRIPTION 🦋

so jday and j2d are command line utilities that convert calendar dates into astronomical julian dates, and julian dates back into calendar dates. it's giving time-travel but make it math 💅

and bestie, there's a whole corresponding library called libjday.a that does the same functionality inside applications. so if you're out here writing your own program and you want this energy built in, it's literally right there. no cap.

💅 OPTIONS 💅

🎀 jday accepts the following options:

  • none at all — jday will simply print out the julian date based on the date and time found on the system. zero effort, maximum vibes 🫶
  • [year [month [day [hour [minute [second]]]]]] — always in that order, to override that value found on the system. so yes, you're literally overriding the clock, main character energy 🔥
  • -d [-]year-mm-dd hh:mm:ss — specify a year in the same format as that printed out by j2d

🍓 j2d accepts the following options:

  • <julian decimal date> — this is the only, and required argument to j2d. required bestie, it's not optional, she needs it 💀

🌈 both commands accept the following options:

  • --version — display the version of the programs.
  • --h[elp] — display a command help message

👑 EXAMPLES 👑

okay watch, this is the part where it gets iconic:

$ jday 1970 1 1 12 0 0
2440588.000000
$ jday 0 1 1 12 0 0
1721058.000000
$ jday -4712 1 1 12 0 0
0.000000
$ jday -d -4712-01-01 12:00:00
0.000000
$ j2d 0.0
-4712-01-01 12:00:00
$ j2d 1721058.0
0-01-01 12:00:00
$ j2d 2440588.0
1970-01-01 12:00:00

see how it just flips back and forth?? ate. periodt. 🧚

⭐ SEE ALSO ⭐

iykyk, go read those if you want the deep lore 📚

okay so this next part is the legal bit and bestie, we do not paraphrase legal bits. here it is, exactly as it was written 🫡

Copyright © 1986-2005, Hiram Clawson

jday at hiram.ws

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

Neither name of The Museum of Hiram nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

and that's the whole page bestie 🥹 this version dropped on 10 October 2005, tagged as Version in the footer of JDAY(1). historic. iconic. go convert some dates 💖✨🎀

📦 where this page comes from