如何找到过去日期以后n天的日期？

Question

I want to find a date that is 57 –working– days after an arbitrary date using date or bash . For instance,

1. today is august 21st,
2. reference date is july 15th,
3. what days will be 57 working days after july 15th?

Answer 1

This should work to just get all days

date -d '7/15/14 +57 days'

To get number of work days (M..F) you can do something lazy like this

#!/bin/bash
days=0
for ((i=1;i>0;i++)) do
  future=$(date -d "7/15/14 +$i days" '+%w')
  ((future!=0 && future!=6)) && ((days++))  # ignore sunday (0) and saturday (6)
  ((days==57)) && date -d "7/15/14 +$i days" && break
done

eg

> ./abovescript
> Thu Oct  2 00:00:00 CDT 2014

Answer 2

Weird solution:

day=21
mon=8
year=2014
days=4

curl -s "http://www.timeanddate.com/scripts/dateserver.php?mode=addweekdays&d1=$day&m1=$mon&y1=$year&type=add&ad=$days&atyp=0&ach=3" | sed -n 's|.*<h2>Result: \(.*\)</h2>.*|\1|p'

prints

Wednesday, August 27, 2014

the date after 4 working days from 2014.08.21

for the

day=15
mon=7
year=2014
days=57

prints

Friday, October 3, 2014