How to swap between versions of the TELEMAC system

It is rather common to have more than one version of the TELEMAC system installed at the same time. Most developers will have at least the current stable and development versions installed at the same time. This article gives some hints on how to set up a system with concurrent versions alongside each other.

= Using the steering file? NO! = In theory, the keyword  in the steering file can be used to swap between versions of ESTEL. However, it is a very bad idea to do so. This is mainly because:
 * the script that lauches ESTEL needs a "dictionary" and it will use the "dictionary" of the version set by default in, regardless of what you have used for
 * ESTEL needs to be used with a particular set of libraries and this cannot be ensured if you change the  string. This is why it is recommended to not put the   keyword into your steering files, the default release numbers selected by the developers will be used instead... and they work.

The rest of this article shows how to reliably switch very quickly between version of ESTEL. The setup is a bit time consuming but after that, a single command is enough to switch (no messy editing of files etc...).

= SYSTELCFG = The TELEMAC system allows several configuration directories. By default, it looks for. However, if the environment variable  is set, it will use its value as the location of the configuration directory.

The method described in this article consists of creating a separate configuration folder for each version of the code. In each configuration folder, the  and   files will point to a specific version of the code.

For instance, create a folder called. Inside this folder, copy a  file where the  [GENERAL] section  is tweaked for version v5p7 of the TELEMAC system. So basically, just set all the " " variables to. Then set the  variable to point to this folder, run   and recompile the whole TELEMAC system:

You will have version v5p7 of the TELEMAC system compiled and configured. Try a few test cases to make sure. Note, in these test cases, make sure the  keyword is not used.

Then create a  folder, edit the   file in this folder and do the same for v5p8:

You will then have both v5p7 and v5p8 compiled and configured on your machine.

= Switching between versions = Providing that the TELEMAC system is configured properly for each configuration directory, switching between versions is now trivial: just set  to point to either   or. Simple!

To switch to version v5p7:

To switch back to v5p8:

= change_systel_version = Actually, to automate the process even more, a script called  is provided in the   which create the relevant code to export   to. This way, you can simply switch between versions by typing " " or " " at the command line.

Note that the root of the TELEMAC system must be stored in the environment variable  for this script to work. Have a look at the typical .bashrc for ESTEL. Also, the use of " " and the backquotes " " is required for the environment variable to be exported properly. You can define simplier shortcuts though, see below.

In the future, the script will be extended to modify the  too so that you can switch between architectures. Be patient...

= Integration in the .bashrc file = The syntax above is quite wordy so it is useful to define a set of small bash functions in your  file to do this automatically. For instance you could use for v5p7:

Define a similar  function. Then you can switch easily:

The typical .bashrc for ESTEL contains some other functions which provide extended functionality when used with the  script above, for instance to navigate quickly to the ESTEL folders.