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Scheduler for laptops which aren't on 24/7.



brew install hughbien/tap/scron

This will install Crystal as a dependency. If you already have a non-homebrew Crystal installed, you can use the --ignore-dependencies crystal option.


Download the latest binary and place it in your $PATH:

wget -O /usr/local/bin/scron
chmod +x /usr/local/bin/scron

MD5 checksum is: 68f821fb86132ad02fc5ba116af696eb

From Source

Checkout this repo, run make and make install (requires Crystal):

git clone
cd scron
make install


Configure scron to run every two hours:

$ crontab -e
0 */2 * * * scron

Configure jobs in $HOME/.scron. This example runs cmd arg1 arg2 at least once every 30 days.

30d cmd arg1 arg2

You can also specify lower bounds like day of week (Su, Mo, Tu, We, Th, Fr, Sa), day of month (23rd), or day of year (4/15):

Mo,Fr    cmd1
1st,23rd cmd2
4/15     cmd3

cmd1 will attempt to run on Monday and Friday. If your machine is off the entire day, it will run as soon as possible. Here's an example timeline:

  • Mo: machine is off, nothing happens
  • Tu: machine is on, cmd1 runs to make up for Monday
  • We: already ran, nothing happens
  • Th: already ran, nothing happens
  • Fr: machine is on, cmd1 runs

An exit status of 0 is considered a success. Anything else is considered a failure and scron will attempt to re-run it again in 2 hours.

$HOME/.scrondb keeps the timestamps of the last run commands.

$HOME/.scronlog has the stdout, timestamps, and exit status of last scheduled commands.


Use make for common tasks:

make build                   # to create a release binary in the bin directory
make build-static            # to build static binary for Linux
make install                 # to copy release binary into system bin (uses $INSTALL_BIN)
make spec                    # to run all tests
make spec ARGS=path/to/spec  # to run a single test
make clean                   # to remove build artifacts and bin directory
make run                     # to run locally
make run ARGS=-h             # to run with local arguments


Copyright 2021 Hugh Bien.

Released under BSD License, see LICENSE for details.