At Commandline Timer Utility

At is a command line tool for waiting until a specific time. It takes both absolute 24 hour times and relative times in hours, minutes, and seconds, and displays a countdown. Daylight saving is taken into account!

It supports Linux and hopefully other POSIX compliant OSes.

Screenshot of a 10 second countdown.

Building

Dependencies:

• C compiler

Run build.sh to build At. This should produce an executable called `/tmp/build/main`.

Source code (.zip, version 2025-11-18)

Usage

$ at 23:00 && echo "It's getting pretty late!"

$ at 16:30:00 && start TheExperiment

$ at +5:00 && play cooking_timer.ogg

$ echo "This system will self destruct in:" && at +01:00:00 && rm -rf /

See `at help` for detailed options.

Short video of a ten second countdown.

License

GPL v3.

Copyright (c) Fudge 2025.