Run OpenSees Interactive at the CLI

Run OpenSees Interactive at the CLI#

Why Start with OpenSees Interactive?#

Before running scripts or submitting jobs to HPC, it’s useful to begin by running OpenSees interactively at the command line. This simple step serves several important purposes:

  • Confirm installation → Running interactively checks that OpenSees is available in your current environment.

  • Check version information → When the interpreter starts, it displays the version number, which is important to record for reproducibility.

  • Understand which interpreter you’re using →

    • Typing OpenSees launches the Tcl interpreter.

    • Typing python launches the Python interpreter, where you must import openseespy.opensees before calling OpenSees commands.

Starting interactively also helps you get comfortable with the prompt and experiment with simple commands one at a time. This is especially helpful when learning OpenSees or troubleshooting a new environment.

Tcl vs. Python in OpenSees#

Both interpreters provide access to the same core simulation engine, but each has its own advantages:

  • OpenSees-Tcl

    • Best for running existing Tcl scripts (many legacy examples are Tcl-based).

    • Provides a minimal environment focused solely on OpenSees commands.

    • Good for quick checks or lightweight scripting.

  • OpenSeesPy (Python)

    • Best for new projects or when integrating OpenSees with the broader scientific Python ecosystem (NumPy, Pandas, Matplotlib, Jupyter notebooks, etc.).

    • Supports modern scripting, automation, and data analysis workflows.

    • Easier to combine OpenSees with pre- and post-processing tools.

In short: use Tcl if you are following older tutorials or running legacy scripts, and use Python for modern workflows and HPC integration.

OpenSees-Tcl#

Start OpenSees-Tcl interactively by simply typing at the terminal:

OpenSees

You’ll see a prompt like:

    OpenSees -- Open System For Earthquake Engineering Simulation
            Pacific Earthquake Engineering Research Center
                    Version xx.xx.xx 64-Bit

(c) Copyright 1999-20xx The Regents of the University of California
                        All Rights Reserved
(Copyright and Disclaimer @ http://www.berkeley.edu/OpenSees/copyright.html)


OpenSees >

You can now enter your commands at the prompt, one at a time, as shown below:

OpenSees > wipe
OpenSees > model BasicBuilder -ndm 2 -ndf 3
OpenSees > exit

OpenSeesPy#

Start python interactively by simply typing at the terminal:

   python

The command-line command will start an interactive session.

Python 3.10.6 | packaged by conda-forge | (main, Aug 22 2022, 20:35:26) [GCC 10.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

You can now enter your commands at the prompt, one at a time, as shown below. You need to import OpenSeesPy before you can run OpenSees commands:

>>> import openseespy.opensees as ops
>>> ops.wipe()
>>> ops.model('BasicBuilder','-ndm',2,'-ndf',3)
>>> exit()
Process 0 Terminating
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