What you'll need
- A flash drive big enough for 2 OS's (the smallest that would work is probably 4GB unless you use like DSL and Puppy Linux).
- UNetBootin, you'll find that here
- The ability to follow directions
So, now that I can assume you have the above lets begin.Steps
1. Download the OS of your choice (windows, linux, mac, doesn't matter) and save it to a location you'll remember (might I suggest the Desktop for easy access).
2. So now that we have our OS we're going to start up UNetBootin and fill in the areas. Since I had you obtain your OS earlier you will focus on the bottom of the window and click the circle next to the word "Diskimage".
3. After you fill in that circle you need to make sure that the drop-down box shows the word ISO, it should automatically but just in case. Then continuing the line select the location of the ISO file.
4. Now you have to do this part carefully - not because it's hard but because if you pick the wrong drive your going to have a big mess on your hands. Assuming your following this for it's purpose (to create a multibootable USB) then select "USB Drive" as the type from the drop down menu. Now here is where you have to be careful, make sure you have your Flash Drive plugged in if it's already not at this point and note it's drive letter (if you miss it just open up "Computer" and on the left hand side it will say by the words "Removable Drive" or whatever it's called for you. Now that we know what letter it is select it in the drop-down menu after the word "Drive".
5. Now, if your looking at UNetBootin you'll see I skipped an option, so I'll cover it now. This is only relevant if your using Ubuntu so disregard it if your not. The last box is for you to pick how much space you want to reserve across reboots, once again it only applies to Ubuntu. For this I recommend at least 900MB but then again that's just me. So now that that's all done hit o k and it will do it's thing.
6. Now that it put the files on your Flash drive reboot and go to your boot menu (Button varies but for Windows 7 it's Esc) and select your Flash drive from the list. If it boots up into your chosen OS then your good. Now restart again and boot back into whatever you normally us.
7. Now UNetBootin only allows 1 OS at a time because it formats your USB as part of it's process which wipes it clean so your going to need to make a folder on your desktop and name it whatever Ex. BT5 and put all of the files in there.
8. Repeat steps 1-7
9. O k, now that we know your second OS runs properly and we have your first in a folder we're going to open up the folder on your desktop and the flash drive.
10. copy all of the files except for those I'll list in a second from your first OS in this case we'll stick with BT5 to, let's say, Debian. The files that your not going to copy over are the following:
11. Now that that's done we're going to open up the syslinux.cfg file from our folder labeled BT5 (or whatever your first OS was) and copy the last four lines, they should look something like this...label ubnentry0
menu label puppy
append initrd=/initrd.gz pmedia=cd
*Note: This is from my copy of Puppy Linux as it was more readily available then my other OS's but you get the idea.*
12. Now open up the syslinux.cfg file from your second OS and paste the lines we just copied in between the lines that have label ubnentry1 and ubnentry2. Now we're almost done, before we can save this file you may have noticed the numerical order of the label ubnentries was thrown off when we pasted that in there so what we need to do is go to the last ubnentry (3 I believe) and change it to 4, and then the 2 to a 3 and so on and so forth until you get to the end.
Now you can save the file.
13. Now reboot your computer and go into the boot menu once more and this time it should have both OS's listed and accessible.
So folks, that's my tutorial, I hope it wasn't too much trouble and if you have any questions feel free to ask.