# Installing MESA¶

## Prerequisites¶

### Ensure your system meets the minimum hardware requirements¶

The minimum system requirements for MESA are:

Most laptop or desktop computers built in the last three years will satisfy these requirements.

### Install the MESA SDK¶

Before you install MESA, you need to get the prerequisites. The MESA SDK simplifies this process by providing a prebuilt set of compilers and run-time libraries that should make your MESA install go smoothly. Visit the MESA SDK website for the details of setting it up.

If you would prefer to use ifort (the MESA SDK uses gfortran), that is also an option, so long as you use ifort 14 or later. Even if you choose to use ifort, you should still visit the MESA SDK website to get a feel for the other MESA requirements.

Not using the MESA SDK means you’ll need to replace the file $MESA_DIR/utils/makefile_header with a version customized to your system. There’s a template to get you started at $MESA_DIR/utils/makefile_header_non_mesasdk.

Regardless of whether you use the MESA SDK or ifort, and whether your machine runs MacOS or linux, the output of MESA should be bit-for-bit identical. If it’s not, this is considered to be a bug. (This has been the case since Release 5819 in early January 2014.)

## Installation¶

The simplest way to get the MESA software is to download a zip file of the latest MESA release.

The compressed file is about 2GB, so don’t worry if it takes a little while to download.

The unzipped and installed package will be large, so make sure you have at least 20 GB free on your disk.

When you unzip the file, it will create a directory named mesa-r22.11.1. This will be your main MESA directory. You are free to rename it, just make sure to set MESA_DIR accordingly (see the next section).

The easiest way to make sure that your system is always configured appropriately is to define the necessary environment variables in your shell start-up file. The file that you need to edit will depend on which shell you’re using. You can find out by running echo $0. The default on most Linux distros is bash, in which case you need to edit $HOME/.bashrc. If you don’t set the environment variables in your shell start-up file, you will need to re-define them each time you open a new shell.

The exact paths depend on where you installed MESA and which operating system you are using. After you add these commands to your shell startup file, don’t forget to open a new shell (or source the startup file in an existing one).

Here is an example from a machine that uses bash as its shell (and hence uses export to set variables):

# set MESA_DIR to be the directory to which you downloaded MESA
# The directory shown is only an example and must be modified for your particular system.
export MESA_DIR=/Users/jschwab/Software/mesa-r21.12.1

# set OMP_NUM_THREADS to be the number of cores on your machine

# you should have done this when you set up the MESA SDK
# The directory shown is only an example and must be modified for your particular system.
export MESASDK_ROOT=/Applications/mesasdk
source $MESASDK_ROOT/bin/mesasdk_init.sh  If your machine uses csh as its shell, use setenv instead of export. One caveat is that if you initialize the MESA SDK in your shell profile, you’ll always be using the MESA SDK supplied version of gcc which may be a compatibility issue if you work with other other codes. Alternative (unsupported) initialization scripts are available here. ### Compile MESA¶ Now we are ready to compile the code. This will take a little while, so do something else for a bit or get up and get a cup of coffee. cd$MESA_DIR
./install


Warning

There is no reason to use sudo. The MESA install does not require root privileges.

Once it is done, you should receive the message

************************************************
************************************************
************************************************

MESA installation was successful

************************************************
************************************************
************************************************


Read the linked page that summarizes some best practices to keep in mind throughout the lifecycle of your project.

## Troubleshooting¶

First, confirm that you can reproduce the error. Do

cd $MESA_DIR ./clean ./install  and see if you get the same error. ### Check that your environment variables are set correctly¶ One of the most common issues is unset or incorrectly set environment variables. In the same terminal window where you are trying to install MESA, execute the command: echo$MESA_DIR


and if you’re using the MESA SDK, execute the command:

echo $MESASDK_ROOT  Confirm that these showed the directories where you have installed MESA and the MESA SDK. If they did not, please re-read the instructions on how to Set your environment variables. ### Confirm that you installed the MESA SDK correctly¶ Please check that you followed the MESA SDK installation instructions. Pay particular attention to the prerequisites for your system. ### Consult the FAQ¶ Check to see if there is any information about your problem in the MESA FAQ. If you are using the MESA SDK and are having a problem with installation, you should also consult the MESA SDK FAQ. ### Search the mesa-users mailing list archive¶ Search the mailing list archives to see if someone has had a similar problem in the past. ### Post a question to mesa-users¶ If the previous steps have not solved your problem, send an email message to mesa-users@lists.mesastar.org describing the problem. Please provide the following information: • What version of MESA are you trying to build? • Are you using the MESA SDK? If so, what version? • Describe your computer (machine type, operating system, operating system version). • What is the error message you received? • Attach the $MESA_DIR/build.log file. This includes the output of the build process along with the output of each of the following commands

uname -a
gfortran -v
echo $MESASDK_ROOT echo$PATH
echo \$MESA_DIR