Environment Variables

The following lists environment variables that can effect the way MESA runs.



Location of the mesa source code.


Location of the gyre source code (only needed if running gyre). If you haven’t moved it from the MESA_DIR then set as GYRE_DIR = $MESA_DIR/gyre/gyre.



Location where MESA will store and read cache files. See star_job.defaults cache directories for more details.


Location where mesa will write the cache file temporarily before moving to MESA_CACHES_DIR. If set, this folder MUST be unique for each MESA run. If not set defaults to ./.mesa_temp_cache.


Location of the OP_MONO data files See $MESA_DIR/star/test_suite/radiative_levitation/inlist_radiative_levitation for more details.


By default MESA will look for a file called “inlist” in the local working directory for its configuration. This overrides the filename and can point to a file somewhere else.


Useful things that are not environment variables.

Command line arguments

./star can accept one argument that overrides the location of the inlist file (see mesa_inlist). This will also override the environment variable mesa_inlist.

./star some_other_inlist_file


Empty file. If present in $MESA_DIR then no compiling is done when ./install is invoked. If present in a sub folder (e.g MESA_DIR/eos) then no compiling is done in the sub-folder


Empty file. Similar to skip_build, but this will skip the compile time tests. If placed in a sub-folder then only the tests in that folder are skipped


These options are for developers, you do not need them for normal usage. If you use them and things break then stop using them.


Bypass checks done at compile time for checking if MESA_DIR is set.


If set, then we do not use the temp cache mechanism, writing cache files directly to the $MESA_DIR/data/ folder.


If set disables the generation of backtraces when we call mesa_error() this is mostly helpful on macs as they don’t generate useful backtraces.


When set to 1 this will turn on a series of compile time checks as well as certain inlist options designed to catch floating point exceptions. This should not be set during a normal run.