The following refers to mtools usage in floppy images. (Useful for virtual machines such as QEMU or VirtualBox.)
Copying a file to floppy image:
$ mcopy-iDisk.imgfile_source::file_target
Copying a file from floppy image to the current directory:
$ mcopy-iDisk.img::file_sourcefile_target
Deleting all files in the disk image
$ mdel-iDisk.img::*.*
The drive character : (colon) has a special meaning. It is used to access image files which are directly specified on the command line using the -i options.[4]