Days between 2 dates

[John Chaff]

Hi:

A colleague told me about this site. I have two dates, 11/26/99 and 03/05/02, for example. It there a UNIX utility to determine the number of days between these two dates? This should be so simple.

Thanks in advance for your help,
John Chaff

[Rajeev Shukla]

There is no utility as such in unix to do that but i am sure its not difficult. I had posted similar programs in C before, let me see if i can find them, but in the mean time i can tell you the logic in C.
Convery both the dates to sec from 1970 using time() function and then substract them and divide them by 3600 you'll get hours and then further divide by 24 to convery into days.

[Ramkumar Devanathan]

John,

Try Clay Stephenson's caljd perl script - it is easy to use. usage details are provided within.

https://www.beepz.com/personal/merijn/caljd-2.2.pl

- ramd.

[Steven E. Protter]

There is a wonderful utility that does this written by A. Clay Stephenson.

caljd.sh
caljd.pl

http://www.hpux.ws/merijn/caldj-2.2.sh

http://www.hpux.ws/merijn/caljd-2.2.pl

These will do the trick. Well documented, easy to use.

SEP

[A. Clay Stephenson · Accepted solution]

This here is right easy.

#!/usr/bin/sh
DT1="11/26/99"
DT2="03/05/02"

DIFF=$(( $(caljd.sh -c -C -S "/" ${D2}) - $(caljd.sh -c -C -S "/" ${D1}) ))
echo "Difference = ${DIFF} days."

You will need a recent version of caljd.sh because I added the -C option to interpret 2-digit years as recent years rather than 1st-century CE dates. I do assume that you meant 1999CE rather than 99CE. 99CE would give ctime() functions fits. Invoke as caljd.sh -u for full usage but this should be exactly what you want.


Attached is caljd.sh, Version 2.22.

[A. Clay Stephenson]

And here is the Perl version, if you prefer. The arguments are exactly the same.

Attached is caljd.pl, Version 2.22p.

[A. Clay Stephenson]

Ooops, John, I'm an idiot.

THIS HERE:
DIFF=$(( $(caljd.sh -c -C -S "/" ${D2}) - $(caljd.sh -c -C -S "/" ${D1}) ))
SHOULD BE:
DIFF=$(( $(caljd.sh -c -C -S "/" ${DT2}) - $(caljd.sh -c -C -S "/" ${DT1}) ))

No points please, Clay.

[John Chaff]

Thanks everybody. That is a great script. I have one more question. I would like to print the usage messages but nothing goes to the printer when I type "caljd.sh -u|lp" and also if I use "caljd.sh -u|more" it scrolls off the screen without pausing. I'm confused.

Thanks,
John Chaff

[Robert-Jan Goossens]

Hi John,

# cd /tmp
# nohup caljd.sh -u
Sending output to nohup.out
# lp nohup.out

Regards,
Robert-Jan.

[A. Clay Stephenson]

Like good UNIX scripts, usage and error messages go to stderr rather than stdout and that is your problem. Stdout should only be used for output.


It's trivially easy, just redirect stderr (file descriptor 2) onto stdout (fdes 1), viz:
caljd.sh -u 2>&1 | lp
OR
caljd.sh -u 2>&1 | more

That should fix you, Clay.

[John Chaff]

Thanks everybody for the quick and accurate solutions.