Creating Bootable USB OS Installer

This is an old stuff but I decided to write this as this is one of indispensable  utility for me for a long time.
It allows you to have multiple OS installer in an USB flashdisk. Although you can have several Android and Linux installer in one flashdisk, it only allowed 1 version of Windows.
The official site:
https://sourceforge.net/projects/multisystem/

Watch out with the language, since this app is originally French, but overall is very good.

For easier method of install (Ubuntu derived / PPA) you can use:
$ sudo apt-add-repository 'deb http://liveusb.info/multisystem/depot all main' 
$ wget -q -O - http://liveusb.info/multisystem/depot/multisystem.asc | sudo apt-key add - 
$ sudo apt-get update
$ sudo apt-get install multisystem


Source:
https://www.unixmen.com/create-multiboot-usb-ubuntu-using-multisystem/

Compressing PDF File using (ghost)script

Dealing with Big PDF File can be pain in the a** especially when using slow internet connection or limited space on server.
Thus I've come across script on make things easier. Here's the script:
$ ghostscript -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf

You can get more explanation at:
https://www.internalpointers.com/post/compress-pdf-file-ghostscript-linux
or
https://gist.github.com/firstdoit/6390547

You might also want to check on pdftk and pdfchain on extracting and combining pdf