o Removed --interactive mode, a miniature shell whose primary purpose

was to hide command line arguments from the process list. It had
  been broken (would segfault during the second scan) since before May
  2009 until February 2010 and was rarely used. The fact that it was
  broken was reported by Juan Carlos Castro y Castro.

See http://seclists.org/nmap-dev/2009/q2/464 and
http://seclists.org/nmap-dev/2010/q1/688 for report and discussion.

docs/refguide.xml

@@ -4167,31 +4167,6 @@ hosts with at least one
       </varlistentry>
 
 
-      <varlistentry>
-        <term>
-          <option>--interactive</option> (Start in interactive mode)
-          <indexterm><primary><option>--interactive</option></primary></indexterm>
-          <indexterm><primary><option>interactive mode</option></primary></indexterm>
-        </term>
-        <listitem>
-
-          <para>Starts Nmap in interactive mode, which offers an
-          interactive Nmap prompt allowing easy launching of
-          multiple scans (either synchronously or in the
-          background). This is useful for people who scan from
-          multi-user systems as they often want to test their
-          security without letting everyone else on the system know
-          exactly which systems they are scanning. Use
-          <option>--interactive</option> to activate this mode and then type <keycap>h</keycap> for
-          help. This option is rarely used because proper shells
-          are usually more familiar and feature-complete.  This option
-          includes a bang (!) operator for executing shell commands,
-          which is one of many reasons not to install Nmap
-	  setuid root.<indexterm><primary>setuid, why Nmap shouldn't be</primary></indexterm>
-          </para>
-        </listitem>
-      </varlistentry>
-
       <varlistentry>
         <term>
           <option>-V</option>; <option>--version</option> (Print version number)