Illegal option --
usage: /usr/bin/geographiclib-get-magnetic [-p parentdir] [-f] [-d] [-h] magneticmodel...

This program downloads and installs the datasets used by the
GeographicLib::MagneticModel class and the MagneticField tool to compute
magnetic fields.  magneticmodel is one of more of the names from this
table:

                                  size (kB)
  name     degree    years      tar.bz2  disk
  wmm2010    12    2010-2015      2       3
  wmm2015    12    2015-2020      2       3  *deprecated*
  wmm2015v2  12    2015-2020      2       3
  wmm2020    12    2020-2025      2       3
  wmm2025    12    2025-2030      2       3
  wmmhr2025 133    2025-2030     37     281
  igrf11     13    1900-2015      7      25
  igrf12     13    1900-2020      7      26
  igrf13     13    1900-2025      7      28
  igrf14     13    1900-2025      7      29
  emm2010   739    2010-2015   3700    4400
  emm2015   729    2000-2020    660    4300
  emm2017   790    2000-2022   1740    5050

The size columns give the download and installed sizes of the datasets.
In addition you can specify

  all = all of the supported magnetic models
  minimal = wmm2025 igrf14

-p parentdir (default /usr/share/GeographicLib) specifies where the
datasets should be stored.  The "Default magnetic path" listed when running

  MagneticField -h

should be parentdir/magnetic.  This script must be run by a user with
write access to this directory.

Normally only datasets which are not already in parentdir are
downloaded.  You can force the download and reinstallation with -f.
The -f flag also let you download new models (not yet in the set
defined by "all").

If -d is provided, the temporary directory which holds the downloads,
$TMPDIR/magnetic-XXXXXXXX or /tmp/magnetic-XXXXXXXX,
will be saved.  -h prints this help.

For more information on the magnetic models, visit

  https://geographiclib.sourceforge.io/C++/doc/magnetic.html