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Display a Lissajous curve in text
Use Ruby's standard Curses module to display a Lissajous curve in the console. Replace the "0.2" with different numbers for different curves.

Rotate a pdf by 90 degrees CW

a fast way to repeat output a byte
the speed is about 500MB/s on my machine. i think it's fast enough to output not too many bytes. while a C program may output 1GB per sencond on my machine. if the size is not the power of 512,you may change the bs and count in dd.

Convert all MySQL tables and fields to UTF8
This loops through all tables and changes their collations to UTF8. You should backup beforehand though in case some data is lost in the process.

Use AWS CLI and JQ to get a list of instances sorted by launch time
Use the AWS CLI tools to generate a list instances, then pipe them to JQ to show only their launch time and instance id. Finally use sort to bring them out in runtime order. Find all those instances you launched months ago and have forgotten about.

print text in colors green, cyan, blue or red (see sample output for usage)

Set laptop display brightness
Run as root. Path may vary depending on laptop model and video card (this was tested on an Acer laptop with ATI HD3200 video). $ cat /proc/acpi/video/VGA/LCD/brightness to discover the possible values for your display.

check open ports without netstat or lsof

dump 1KB of data from ram to file

Remote screenshot
Admittedly, I'd never have thought of this without the earlier examples, but here's one that you can execute from your workstation to just display the image from another, without separately doing a file transfer, etc. By the way, I hear a loud beep coming from the other room, so I guess it's not too stealthy :-D


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