Mac crontab: Creating MacOS startup jobs with crontab, er, launchd

Table of Contents1 - macOS: crontab, launchd, and launchctl2 - Running a simple command every minute with Mac launchd3 - 1) Move to the $HOME/Library/LaunchAgents directory4 - 2) Create a Mac plist file to describe your job5 - 3) Tell MacOS about your Mac plist launchd file6 - 4) How Mac launchd works with system reboots7 - An important note about root and sudo access8 - MacOS launchd, launchctl, and plist resources9 - MacOS startup jobs: cron and crontab, launchd and launchctl

MacOS crontab FAQ: How do I run a Unix job (or shell script) through the MacOS crontab facility? I keep trying to edit my Mac crontab file, but my Mac won't save my crontab changes, or run my program.

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macOS: crontab, launchd, and launchctl

Way back when (~2012-2014), I found that the Mac crontab command was deprecated on MacOS, and the Apple documentation encouraged you to use their launchd facility. Here’s a blurb from Apple's crontab man page:

“Darwin note: Although cron(8) and crontab(5) are officially supported under Darwin, their functionality has been absorbed into launchd(8), which provides a more flexible way of automatically executing commands. See launchctl(1) for more information.”

How to use the Linux ‘scp’ command without a password to make remote backups alvin August 7, 2018 - 11:25am

Summary: How to create a public and private key pair to use ssh and scp without using a password, which lets you automate a remote server backup process.

Over the last two years I've ended up creating a large collection of websites and web applications on a variety of Linux servers that are hosted with different companies like GoDaddy and A2 Hosting. I recently embarked on a mission to automate the backup processes for all these sites, and as a result of this effort, I thought I'd share what I've learned here.

Unix find command: How to move a group of files into the current directory

I just bought a bunch of MP3 music files from Amazon, and when I downloaded the zip file they provide onto my Mac, it was a bunch of files in a bunch of subdirectories; not really convenient to work with when you’re trying to import them into iTunes. So I used this Unix find command to move all of the music files from the subdirectories they were scattered in into the root directory that was created when I expanded the zip file:

cd Amazon-Music-Folder
find . -type f -exec mv {} . \;

If you ever need to either copy or move a bunch of files with a single command, I hope this example shows the correct find command syntax for your needs. (If you need to copy the files, use the cp command instead of the mv command.)

Why is my MacBook warm when the lid is closed (in sleep mode)?

Table of Contents1 - Troubleshooting2 - My solution3 - Possible problem: Energy Saver settings4 - Possible problem: Bluetooth settings5 - More information6 - Summary

When I woke up last night it was a little windy outside, so I decided to unplug my MacBook Pro because the power tends to flicker here. When I picked up the MacBook I noticed that it was very warm, even though the lid was closed and it was in sleep mode. This morning I decided to dig into the “Why is my MacBook hot even though the lid is closed and it’s in sleep mode” question.

Notes from February 4, 2018 (decision journals, Mayan civilization, more)

Farnam Street has been an interesting blog lately, including this post about keeping a decision journal, and this post about the rules of the road of investing.

In other news, reports that researchers have found a sprawling Maya network discovered under a Guatemalan jungle. has a nice pie chart that shows how Apple makes its money (hint: 70% comes from the iPhone, 7% from the Mac). has this article, 21 questions Amazon asks its job candidates.

Finally, here’s a series of tweets where Alastair McAlpine “asked some of my terminal paediatric palliative care patients what they had enjoyed in life, and what gave it meaning.” (Highly recommended reading.)

How to show the largest files under a directory on Mac OS X (Unix) alvin December 23, 2017 - 1:00pm

Here’s an example that shows how to find the largest files under a directory on MacOS and Linux/Unix systems.

A du/sort command to show the largest files under a directory on Mac OS X

The Unix/Linux command that worked for me on my MacOS system is this:

$ du -a * | sort -r -n | head -10

du is the disk usage command, and the -a flag says, “Display an entry for each file in a file hierarchy.” Then I use the sort command to sort the du output numerically and in reverse. After that, head -10 shows only the first ten lines of output. In the Music folder on my Mac the command and output look like this: