# Control & input data¶

Input data
• The CONTROL file

Flex_extract needs a number of controlling parameters to decide on the behaviour and the actual data set to be retrieved. They are initialised by flex_extract with certain default values which can be overwritten with definitions set in the so-called The CONTROL file.

For a successfull retrieval of data from the ECMWF MARS archive it is necessary to understand these parameters and to set them to proper and consistent values. They are described in The CONTROL parameters section.

Furthermore, some CONTROL file examples are provided, and in CONTROL file changes changes to previous versions and downward compatibilities are described.

• ECMWF user credential file ECMWF_ENV

flex_extract needs to be able to reach ECMWF servers in the remote mode and the gateway mode. Therefore a ECMWF user credential file ECMWF_ENV is created during the installation process.

• Templates

A number of files which are created by flex_extract are taken from templates. This makes it easy to adapt, for example, the job scripts with regard to the settings for the batch jobs.

Controlling

The main tasks and the behaviour of flex_extract are controlled by the Python scripts. There are two top-level scripts, one for installation called install, and one for execution called submit. They interpret a number of command-line arguments which can be seen by typing --help after the script call. Go to the root directory of flex_extract to type:

cd flex_extract_vX.X
python3 Source/Python/install.py --help
python3 Source/Python/submit.py --help


With version 7.1, we provide also wrapper shell scripts setup and run which set the command-line parameters, do some checks, and execute the corresponing Python scripts install.py and submit.py, respectively. It might be faster and easier for beginners if they are used. See Usage for information on how to use them.

flex_extract also creates the Korn shell scripts The compilation job script compilejob.ksh and The job script job.ksh which will be sent to the ECMWF servers in the remote mode and the gateway mode for starting batch jobs.

The Fortran program is compiled during the installation process using the The Fortran makefile for calc_etadot.

To sum up, the following scripts control flex_extract:

Installation
Execution