I am asking how to create the .img file like in alot of floppy images and usb.img files-are they the same and how are they made-is their a similar script like "make_iso.sh", except it would be "make_img.sh?
thanks.

Look at the mtools package for formatting floppies. For usb drives, they are more like hard drives, so you can create any filesystem you want for them. Simply create an empty file of the size you need, and then format the file using the filesystem you will be using, such as fsck.vfat for example. Then you can mount the file using the loop device and use it normally.

If you want a bootable usb device, you can simply use grub-install and write to the MBR of the usb device.

On some distro's you can install to a directory (e.g. SuSE) to install a Linux system there. A distro designed to run off a pendrive may be bettter for this. For example, for pendrives, use ext2 instead of ext3. Journaling results in more writes to the device. Don't have a swap partition or file on a solid state device.

OK-what I'm saying is-how to create/make an ".img" file-like a ".iso" file.
For example-archlinux has a "archlinux-2009.02-2-ftp-i686.img"
How is this file type made??

OK-I figured it out, an ".img" file is basically the same as a ".iso" file.
To make one, take any iso-let's say goblinx-2.7-Micro.iso, extract the iso contents to a folder-right-click on iso-select "extract here", a folder named goblinx-2.7-micro will appear. Now, go into the folder and then into the "goblinx" folder. here you will find a script called "make_iso.sh", move or copy this script into the "boot" folder(otherwise it won't work). Now, right-click on the make_iso.sh and select "properties", then select "permissions", check the box that says-"allow executing file as program".
Now, double left click on make_iso.sh, a box will appear that says "run in terminal/display/run", choose run in terminal, a terminal will appear asking you for the name of the iso instead of naming it myiso.iso, name it myiso.img and a .img file will be made.
Actually I just figured out that just renaming an iso file to .img changes it-der?

An ISO file tends to mean it is an image of a CDROM. It uses the iso-9660 filesystem. The ISO is commonly used as a truncated form of ISO-9660. This is different than what a floppy image would be or a usb pendrive.

A floppy usually uses the fat-16 filesytem.

The extension is mostly a convenience. Don't rely on it. Also extensions often have several different definitions. You can use the "file" command to determine what a file actually is. For devices you can use "sudo fdisk -s /dev/<device_node>" to determine the filesystem. ( or udevinfo -q env -n /dev/<device_node> ). Pay attention to what you are working with as much or more than what the extension is.

To create from USB/CD/FD

# dd if=/dev/devicetoclone of=isoedfile.iso


To create your own ISO:

# mkisofs -R -o <name_new.iso> <directory_where_the_files_are>

Most important Options:
-posix-H Follow sylinks encountered on command line
-posix-L Follow all symlinks
-posix-P Do not follow symlinks (default)
-o FILE, -output FILE Set output file name
-R, -rock Generate Rock Ridge directory information
-r, -rational-rock Generate rationalized Rock Ridge directory info
-J, -joliet Generate Joliet directory information
-print-size Print estimated filesystem size and exit
-udf Generate UDF file system
-dvd-video Generate DVD-Video compliant UDF file system
-iso-level LEVEL Set ISO9660 level (1..3) or 4 for ISO9660 v 2
-V ID, -volid ID Set Volume ID
-graft-points Allow to use graft points for filenames
-M FILE, -prev-session FILE Set path to previous session to merge