How to generate a date in ISO 8601 format (UTC time) with an offset X days into the future?

Question

When calling an API, I need to provide a start time and an end time in ISO 8601 format (UTC time).

I want to call the API in a CRON job, so I can't manually create the date-time(s).

How can I use the date command to achieve what I want?

Note: I have already read other questions, where the answers show how to output the current date-time, like TZ=GMT date +"%Y-%m-%dT%H:%M:%SZ". This doesn't provide a solution for outputting a date-time into the future.

Example API payload:

{
  "displayName": "string",
  "endDateTime": "2024-03-12T07:06:44.266Z",
  "startDateTime": "2024-03-12T07:06:44.266Z"
}

You've tagged with Debian and Ubuntu. Which is it? – Chris Davies Mar 12 '24 at 08:17 — Chris Davies, Mar 12 '24 at 08:17

score 1 · Answer 1 · answered Mar 12 '24 at 07:48

1

How far into the future?

 date --date=tomorrow
 date --date='1 year'
 date --date='3 days 1 year'

answered Mar 12 '24 at 07:48

user10489

6,740

Thank you, but how can I format it as ISO 8601 format (UTC time)? – Shuzheng Mar 12 '24 at 08:02
@Shuzheng have you checked man date (perhaps searching for 8601)? – Chris Davies Mar 12 '24 at 08:15
You said you had already read other answers on the format so I assumed you figured that out. – user10489 Mar 12 '24 at 11:21
1

@Shuzheng Use the --date and +format options on the same command. – Paul_Pedant Mar 12 '24 at 17:06

How to generate a date in ISO 8601 format (UTC time) with an offset X days into the future?

1 Answers1