+The only exception is that if any of the I<-i>, I<-m>, I<--mount>,
+I<-N> or I<--new> options were given then C<run> is done
+automatically, simply because guestfish can't perform the action you
+asked for without doing this.
+
+=head1 OPENING DISKS FOR READ AND WRITE
+
+The guestfish, L<guestmount(1)> and L<virt-rescue(1)> options I<--ro>
+and I<--rw> affect whether the other command line options I<-a>,
+I<-c>, I<-d>, I<-i> and I<-m> open disk images read-only or for
+writing.
+
+In libguestfs E<le> 1.10, guestfish, guestmount and virt-rescue
+defaulted to opening disk images supplied on the command line for
+write. To open a disk image read-only you have to do I<-a image --ro>.
+
+This matters: If you accidentally open a live VM disk image writable
+then you will cause irreversible disk corruption.
+
+In a future libguestfs we intend to change the default the other way.
+Disk images will be opened read-only. You will have to either specify
+I<guestfish --rw>, I<guestmount --rw>, I<virt-rescue --rw>, or change
+the configuration file C</etc/libguestfs-tools.conf> in order to get
+write access for disk images specified by those other command line
+options.
+
+This version of guestfish, guestmount and virt-rescue has a I<--rw>
+option which does nothing (it is already the default). However it is
+highly recommended that you use this option to indicate that you need
+write access, and prepare your scripts for the day when this option
+will be required for write access.
+
+B<Note:> This does I<not> affect commands like L</add> and L</mount>,
+or any other libguestfs program apart from guestfish and guestmount.