-$ export SIMGRID_ROOT="$HOME/Install/simgrid/"
-$ export SIMGRID_JAVA_ROOT="$HOME/Install/simgrid-java"
-$ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$SIMGRID_ROOT/lib:$SIMGRID_JAVA_ROOT/java
+$ export SIMGRID_ROOT="$HOME/Install/simgrid/" # change it to the path where you installed the SimGrid library
+$ export SIMGRID_JAVA_ROOT="$HOME/Install/simgrid-java" # change it to the path where you installed the java bindings of SimGrid
+$ export LD_LIBRARY_PATH=${LD_LIBRARY_PATH:+$LD_LIBRARY_PATH:}$SIMGRID_ROOT/lib:$SIMGRID_JAVA_ROOT/java