How to take screenshot automatically/ periodically on Mac by script

first, create folder and .sh file by terminal

(on this sample, "screenshot" and "Screencapture.sh")

$ cd

$ mkdir screenshot

$ cd screenshot

$ touch Screencapture.sh

Second,

create shell script

#!/bin/bash

/usr/sbin/screencapture -m -C -T0 -x ~/screenshot/capture_`date +%Y%m%d%H%M`.png

Next, permission.

$ chmod +x Screencapture.sh

Then, open your editor and copy and paste.

<?xml version="1.0" encoding="UTF-8"?>
	<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
	<plist version="1.0">
	<dict>
	<key>Label</key>
	<string>com.example.app</string>
	<key>ProgramArguments</key>
	<array>
	<string>/Users/xxxxx(username)/Screenshot.sh</string>
	</array>
	<key>StartInterval</key>
	<integer>300</integer>
	</dict>
	</plist>

Great, save this file as "com.example.app.plist" and locate to "/Library/LaunchDaemons"

then, run.

launchctl load -w /Library/LaunchDaemons/com.example.app.plist

You will see screen shot each 5 min.

reference
http://www.splinter.com.au/using-launchd-to-run-a-script-every-5-mins-on/