Only load modules once per session in .bashrc

.bashrc

@@ -2,15 +2,19 @@
 # in /etc/profile, i.e. *before* ~/.profile!
 . ~/.env
 
-# setup modules
+# setup modules; only execute once to prevent re-loading impi after loading gcc
+if [ -z "$_MODULES_LOADED" ]; then
+	# set variable to mark modules as loaded
+	_MODULES_LOADED=1
+	export _MODULES_LOADED
 	# hierarchical module system: compiler → mpi → libraries
 	#   Modules fftw-mpi and hdf5-mpi become available after loading a compiler module
 	#   and an MPI library (impi). The available modules are determined by the
 	#   compiler/MPI combination that was loaded (i.e. in this case, fftw-mpi is the
 	#   version compiled with intel and impi).
-#   Currently, loading both compiler modules (gcc and intel) causes problems with the
-#   MODULEPATH that is set up by impi, so make sure to load another compiler only
-#   *after* impi is loaded!
+	#   Currently, loading both compiler modules (gcc and intel) causes problems with
+	#   the MODULEPATH that is set up by impi, so make sure to load another compiler
+	#   only *after* impi is loaded!
 	module load intel
 	module load impi
 	module load fftw-mpi
@@ -27,6 +31,7 @@ module load anaconda
 	module load julia
 	module load gnuplot
 	module load p7zip
+fi
 
 # if running interactively: set MPI variables; else stop
 # see https://www.mpcdf.mpg.de/services/computing/linux/Astrophysics