       server_cntl fileid attribute [value]
              Set or get the value of a socket attribute.

              Attributes are:

              o KEEPALIVE - Keep connection alive.  If SIGPIPE is
              enabled, then it is sent if  connection  is  broken
              and  data is written to the socket.  Note that SIG-
              PIPE is set to be ignored by  the  Tcl  library  to
              support  pipes  to  processes  in the exec and open
              commands.  If  SIGPIPE  is  ignored,  an  error  is
              returned  on  the write.  Use server_send to detect
              dropped connections reliably, Boolean value.

              If value is specifice, the options is set  to  that
              value.  Otherwise, the value is returned.

              This command is provided by Extended Tcl.
