Configuration Options

There are two main ways of configuring NEST at runtime, via the configuration file or command line switches.

NEST configuration file

Upon importing the NEST Python module or starting the nest executable from the command line for the first time, NEST will create a configuration file called .nestrc in your home directory.

By adapting this file, you can set a number of options:

  • The browser for displaying the helpdesk

  • The pager for showing the built-in help in the terminal

  • The mpirun command for parallel execution of the testsuite

In case your MPI Implementation requires special options (e.g. --oversubscribe to allow the use of more processes than available compute cores in OpenMPI versions above 3.0), you can add them to the mpirun command as shown in the following example:

[/integertype /stringtype /stringtype]
[/numproc     /executable /scriptfile]
 () [
  (mpirun --oversubscribe -np ) numproc cvs ( ) executable ( ) scriptfile
 ] {join} Fold
} Function def

Command line switches for the nest executable


nest --help

to find out about NEST’s command-line parameters.

usage: nest [options] [ - | file [file ...] ]
  file1 file2 ... filen     read SLI code from file1 to filen in ascending order
                            Quits with exit code 126 on error.
  -   --batch               read SLI code from stdin/pipe.
                            Quits with exit code 126 on error.
  -c cmd                    Execute cmd and exit
  -h  --help                print usage and exit
  -v  --version             print version information and exit
      --userargs=arg1:...   put user defined arguments in statusdict::userargs
  -d  --debug               start in debug mode (implies --verbosity=ALL)
      --verbosity=ALL       turn on all messages.
                            show messages of this priority and above.
      --verbosity=QUIET     turn off all messages.

SLI scripts

Scripts can be run by typing:

<nest_install_dir>/nest <file>

If you are a Vim user and require support for SLI files, please refer to our Vim support for SLI files.

Supplying SLI scripts with parameters

Using the --userargs=arg1:... command line switch, it is possible to supply a SLI script with parameters from the outside of NEST. A common use case for this are parameter sweeps, where the parameters are defined in a bash script and multiple instances of NEST are used to test one parameter each. A bash script for this could look like this:

for lambda in `seq 1 20`; do
  for gamma in `seq 1 5`; do
    nest --userargs=lambda=$lambda:$gamma=$gamma simulation.sli

The corresponding SLI script simulation.sli could use the supplied parameters like this:

/args mark statusdict/userargs :: {(=) breakup} Map { arrayload pop int exch cvlit exch } forall >> def
args /lambda get ==

The first line first gets the array of user supplied arguments (userargs) from the statusdict and breaks each element at the “=”-symbol. It then converts the first element (lambda, gamma) to a literal and the second argument (the number) to an integer. Using mark and >>, the content of the userargs array is added to a dictionary, which is stored under the name args. The second line just prints the content of the lambda variable.