Echo Unix timestamp using the date command
By default, the Unix timestamp (epoch) is calculated in UTC, so there will be no difference in it regardless of the timezone.
$ date +%s
Storing timestamp in a variable, and echo it
$ timestamp=$(date +%s)
$ echo $timestamp
What is epoch time (Unix timestamp)?
The Unix epoch is the time 00:00:00 UTC on 1 January 1970. Current epoch time is the number of seconds counted from there.