Check command success in bash

I'd do:

ok=true
if dd ...; then
  sync
else
  ok=false
fi

cp ... || ok=false

if "$ok"; then
  mformat...
fi

Since you are using bash just add:

set -e

to the beginning of your script and it will fail whenever any of the commands failed.

Try with:

dd <command>
DD_EXIT_STATUS=$?

cp <command>
CP_EXIT_STATUS=$?

if [[ DD_EXIT_STATUS -eq 0 && CP_EXIT_STATUS -eq 0 ]]; then
    format floppy disk
else
    ... other stuff ...
fi