Question

I want to be able to specify a time value in the past, down to the second. I’ll be using this with github. How do I do this?

Answer 1

Your question is unclear.

The date command takes a -d or --date=... option that lets you specify a date. The format of the specified date is fairly flexible. There are also options to control the output format. For example:

$ date -d 'Oct 1 01:23:45'
Sat Oct  1 01:23:45 PDT 2011
$ date -d 'Oct 1 01:23:45' +'%F %T'
2011-10-01 01:23:45

date --help or info date for more details.

You say you’ll “be using this with github”. How will you be using it with github? Do you want to pass a formatted date string to some git command? Details, please.