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NAME

       slave - Functions for starting and controlling slave nodes.

DESCRIPTION

       This  module  provides functions for starting Erlang slave nodes. All slave nodes that are
       started by a master terminate automatically  when  the  master  terminates.  All  terminal
       output produced at the slave is sent back to the master node. File I/O is done through the
       master.

       Slave nodes on other hosts than the current one are started with the ssh program. The user
       must be allowed to ssh to the remote hosts without being prompted for a password. This can
       be arranged in a number of ways (for details, see the ssh  documentation).  A  slave  node
       started  on  the  same  host  as  the  master inherits certain environment values from the
       master, such as the current directory and the  environment  variables.  For  what  can  be
       assumed  about  the  environment  when  a  slave  is  started  on  another  host,  see the
       documentation for the ssh program.

       An alternative to the ssh program can be specified  on  the  command  line  to  erl(1)  as
       follows:

       -rsh Program

       Note  that  the  command  specified with the -rsh flag is treated as a file name which may
       contain spaces. It is thus not possible to include any command line  options.  The  remote
       node  will be launched as "$RSH" "$REMOTE_HOSTNAME" erl -detached -noinput ..., so the erl
       command must be found in the path on the remote host.

       The slave node is to use the same file system at the master. At least, Erlang/OTP is to be
       installed  in  the  same  place  on both computers and the same version of Erlang is to be
       used.

       A node running on Windows can only start slave nodes on the host on which it is running.

       The master node must be alive.

EXPORTS

       pseudo([Master | ServerList]) -> ok

              Types:

                 Master = node()
                 ServerList = [atom()]

              Calls pseudo(Master, ServerList). If you want to start a node from the command line
              and  set  up a number of pseudo servers, an Erlang runtime system can be started as
              follows:

              % erl -name abc -s slave pseudo klacke@super x --

       pseudo(Master, ServerList) -> ok

              Types:

                 Master = node()
                 ServerList = [atom()]

              Starts a number of pseudo servers. A pseudo server is a server  with  a  registered
              name  that does nothing but pass on all message to the real server that executes at
              a master node. A pseudo server is an intermediary that only has the same registered
              name as the real server.

              For  example,  if  you have started a slave node N and want to execute pxw graphics
              code on this node, you can start server pxw_server as a pseudo server at the  slave
              node. This is illustrated as follows:

              rpc:call(N, slave, pseudo, [node(), [pxw_server]]).

       relay(Pid) -> no_return()

              Types:

                 Pid = pid()

              Runs  a  pseudo  server. This function never returns any value and the process that
              executes the function receives messages. All messages received are simply passed on
              to Pid.

       start(Host) -> {ok, Node} | {error, Reason}

       start(Host, Name) -> {ok, Node} | {error, Reason}

       start(Host, Name, Args) -> {ok, Node} | {error, Reason}

              Types:

                 Host = inet:hostname()
                 Name = atom() | string()
                 Args = string()
                 Node = node()
                 Reason = timeout | no_rsh | {already_running, Node}

              Starts  a  slave node on host Host. Host names need not necessarily be specified as
              fully qualified names; short names can also be used. This  is  the  same  condition
              that applies to names of distributed Erlang nodes.

              The  name  of  the started node becomes Name@Host. If no name is provided, the name
              becomes the same as the node that executes the call (except the host name  part  of
              the node name).

              The slave node resets its user process so that all terminal I/O that is produced at
              the slave is automatically relayed to the master. Also, the file process is relayed
              to the master.

              Argument  Args is used to set erl command-line arguments. If provided, it is passed
              to the new node and can be used for a variety of purposes; see erl(1).

              As an example, suppose that you want to start a slave node at host H with node name
              Name@H and want the slave node to have the following properties:

                * Directory Dir is to be added to the code path.

                * The Mnesia directory is to be set to M.

                * The Unix DISPLAY environment variable is to be set to the display of the master
                  node.

              The following code is executed to achieve this:

              E = " -env DISPLAY " ++ net_adm:localhost() ++ ":0 ",
              Arg = "-mnesia_dir " ++ M ++ " -pa " ++ Dir ++ E,
              slave:start(H, Name, Arg).

              The function returns {ok, Node}, where Node is the name of the new node,  otherwise
              {error, Reason}, where Reason can be one of:

                timeout:
                  The master node failed to get in contact with the slave node. This can occur in
                  a number of circumstances:

                  * Erlang/OTP is not installed on the remote host.

                  * The file system on the other host  has  a  different  structure  to  the  the
                    master.

                  * The Erlang nodes have different cookies.

                no_rsh:
                  No  remote  shell  program  was found on the computer. Note that ssh is used by
                  default, but this can be overridden with the -rsh flag.

                {already_running, Node}:
                  A node with name Name@Host already exists.

       start_link(Host) -> {ok, Node} | {error, Reason}

       start_link(Host, Name) -> {ok, Node} | {error, Reason}

       start_link(Host, Name, Args) -> {ok, Node} | {error, Reason}

              Types:

                 Host = inet:hostname()
                 Name = atom() | string()
                 Args = string()
                 Node = node()
                 Reason = timeout | no_rsh | {already_running, Node}

              Starts a slave node in the same way as start/1,2,3, except that the slave  node  is
              linked  to  the  currently executing process. If that process terminates, the slave
              node also terminates.

              For a description of arguments and return values, see start/1,2,3.

       stop(Node) -> ok

              Types:

                 Node = node()

              Stops (kills) a node.