Better Cron Emails

In assuming you run cron jobs all the time, on all your systems, like I do, you've probably set the crontab options or the MAILTO variable within /etc/crontab configuration file or utilized stderr and stdout redirects.

There is a better way!

Meet Cronic, a shell script by Chuck Houpt

to help control the most annoying feature of cron: unwanted emailed output, or 'cram' (cron spam).

Basic Usage

Instead of writing:

* * * * * myscript >/dev/null 2>&1

you can now write:

* * * * * cronic myscript

You can avoid sweeping all cron errors under the rug, as we do with stderr and stdout redirection to the /dev/null black hole while simultaneously cleaning up the readability of your scripts.

Get it on Github

The Cronic script is available on Github via the community here: justincase/cronic. That version is v2 and I've submitted a PR to upgrade things to v3.

If you need v3 now, fork my copy at thinkjrs/cronic.

Installation

If you're a familiar 'nix user just make the script executable and put it somewhere in your path.

'Nix Scripting Step-by-step

For those readers less familiar with 'nix scripting, let's break down step by step how to install Cronic.

Open up your terminal:

1. Clone the repo via git clone git@github.com:thinkjrs/cronic.
2. Change directories into the new repo directory cd cronic.
3. Make cronic executable via chmod +x cronic.
4. Make a bin directory in your user $HOME directory, i.e. mkdir $HOME/bin or mkdir ~/bin.

   Don't worry, if you have a bin directory within your home directory already this will not overwrite it.

5. Make sure that ~/bin is added to your path via .profile, .bash_profile, .zsh_profile, .bashrc, or whatever shell configuration files you use.

For example, on some systems I have the following in my .bashrc:

PATH="$HOME/.local/bin:$HOME/bin:$PATH"
... # more stuff added to the PATH
export PATH # now we export it to be used by the shell

6. Soft-link your executable cronic script to your ~/bin directory. Assuming you're still in your cronic directory from Github (if not, navigate your shell there):

CRONIC_LOC=$(pwd)/cronic # set a temporary shell variable
pushd ~/bin # temporarily go into your ~/bin directory
ln -s $CRONIC_LOC cronic # create a soft-link _to_ the CRONIC_LOC named cronic
popd # return to your original cronic directory from Github

'Nix Extras

You might have noticed the use of popd and pushd above, in addition to creating some ~/bin directory for your user-space cronic script.

These are intentional as built-in programs and/or conventions commonly used in the GNU/Linux community.

• Read more on the Linux Filesystem Hierarchy.
• Dig into pushd and popd

If you're interested in improving overall 'nix skills check out Linux Journey.

I hope you found this useful and thanks for reading!