function mycp ()
{
case $# in
    0)
        # Zero arguments
        # File descriptor 3 duplicates standard input
        # File descriptor 4 duplicates standard output
        exec 3<&0 4<&1
        ;;
    1)
        # One argument
        # Open the file named by the argument for input
        # and associate it with file descriptor 3
        # File descriptor 4 duplicates standard output
        exec 3< $1 4<&1
        ;;
    2)
        # Two arguments
        # Open the file named by the first argument for input
        # and associate it with file descriptor 3
        # Open the file named by the second argument for output
        # and associate it with file descriptor 4
        exec 3< $1 4> $2
        ;;
     *)
        echo "Usage: mycp [source [dest]]"
        return 1
        ;;
esac
# Call cat with input coming from file descriptor 3
# and output going to file descriptor 4
cat <&3 >&4
# Close file descriptors 3 and 4
exec 3<&- 4<&-
}