biff

A simple utility for doing datetime arithmetic, parsing and formatting. More information: https://github.com/burntsushi/biff.

• Print the current time in a format of your choosing:

biff time fmt {{[-f|--format]}} rfc3339 now

• Print multiple relative times in one command:

biff time fmt {{[-f|--format]}} '%c' now -1d 'next sat' 'last monday' '9pm last mon'

• Print the current time in another time zone, and round it the nearest 15 minute increment:

biff time in Asia/Bangkok now | biff time round {{[-i|--increment]}} 15 {{[-s|--smallest]}} minute

• Convert a time between two different time zone:

TZ='Japan' biff time in America/New_York 02:30

• Print a past or future time relative to current time:

biff time add {{-1d|1d|1w|-1m|1y|...}} now

• Add a complex duration to the current time:

biff time add '1 week, 12 hours ago' now

• Find the duration since a date in the past and round it to the desired precision:

biff span since 2025-01-20T12:00 {{[-l|--largest]}} year

• Find timestamps in a log file and reformat them into your local time in place:

biff tag lines /tmp/access.log | biff time in system | biff time fmt {{[-f|--format]}} '%c' | head {{[-n|--lines]}} 3 | biff untag {{[-s|--substitute]}}