Timezone offsets without the ceremony

A small command-line helper for answering one question: what time is it there, when it is this time here?

Every calendar app can do this. Most of them need six clicks and a mouse. tzdiff does it in one line, reads the IANA database that is already on your machine, and prints plain text you can pipe somewhere else.

$ tzdiff --from Europe/Riga --to Asia/Tokyo 09:30
09:30 Europe/Riga  ->  15:30 Asia/Tokyo   (+6h, same day)

What it does

Converts a wall-clock time between any two zones, with day rollover shown explicitly.
Prints a comparison table for several zones at once.
Marks daylight-saving transitions in the window you asked about, which is the part people usually get wrong.
Reads /usr/share/zoneinfo directly. No bundled copy that drifts out of date.

What it does not do

No calendar integration, no meeting scheduler, no daemon, no configuration file. If you need those, you need a calendar, not this.

Status: maintained but quiet. The timezone database changes a few times a year; the code around it does not need to.

Installing

$ ./configure && make
$ sudo make install

Single binary, no runtime dependencies beyond libc and the system zoneinfo files. Builds on Linux, macOS and the BSDs.