.. _starting_the_ecflow_server:

Starting the ecFlow Server
//////////////////////////

The executable ecflow_server is used to start an ecflow_server using the
default port number or that defined by the environment variable
ECF_PORT.

.. code-block:: shell

    cd ECF_dir1
    nohup ecflow_server & # start ecFlow with **default** port 3141    

Multiple ECFs can be run on the same host using different port numbers.
There are two mechanisms for specifying the port number:

-  Using arguments on the command line. i.e. ecflow_server --port=3141

-  Using the Environment variable. ECF_PORT

If both are specified the command line argument takes precedence

.. code-block:: shell

   cd ../ECF_dir2
   ecflow_server –-port=3142& # start ecFlow with port number 3142
   cd ../ECF_dir3
   export ECF_PORT=3143
   ecflow_server &            # starts ecFlow with port number 3143

**Note:** the ECFs are started in different directories so that the
output and checkpoint files are not overwritten

Adding a new server to ecflow_ui adds the definition to the file::

  ~/.ecflowrc/servers. 

This can be modified directly.

You cannot start two ecFlow servers on the same machine with the same
port number. To simplify users wanting their own ecFlow servers we have
a script **ecflow_start.sh** that sets up an ecFlow server using a port
number based on the users own unique user ID

You can check what port numbers are being used, with netstat: To list
all open network ports on your machine, run::
  
  netstat -lnptu
  
Here is a breakdown of the parameters:

-  l - List all listening ports

-  n - Display the numeric IP addresses (i.e., don't do reverse DNS
   lookups

-  p - List the process name that is attached to that port

-  t - List all TCP connections

-  u - List all UDP connections

.. figure:: /_static/ug/starting_the_ecflow_server/image1.png
   :width: 4.02282in
   :height: 2.60417in

   Viewing new ECFLOW servers with ecflow_ui

When using non-default ecFlow servers, ecflow_ui needs to be configured
to recognise the port used. This can be done in the Manage servers dialog.