-gunzip ${SIMGRID_VERSION}.tar.gz
-tar xf ${SIMGRID_VERSION}.tar
-mkdir ${WORKSPACE}/build/${SIMGRID_VERSION}/build
-cd ${WORKSPACE}/build/${SIMGRID_VERSION}/build
+gunzip "${SIMGRID_VERSION}".tar.gz
+tar xf "${SIMGRID_VERSION}".tar
+mkdir "${WORKSPACE}"/build/"${SIMGRID_VERSION}"/build
+cd "${WORKSPACE}"/build/"${SIMGRID_VERSION}"/build