To avoid useless download and rebuild, it's important to set the variable DL_DIR and SSTATE_DIR in your configuration.
```sh
-echo '# reuse download directories' >> $AGL_TOP/site.conf
-echo 'DL_DIR = "$HOME/downloads/"' >> $AGL_TOP/site.conf
-echo 'SSTATE_DIR = "$AGL_TOP/sstate-cache/"' >> $AGL_TOP/site.conf
+echo "# reuse download directories" >> $AGL_TOP/site.conf
+echo "DL_DIR = \"$HOME/downloads/\"" >> $AGL_TOP/site.conf
+echo "SSTATE_DIR = \"$AGL_TOP/sstate-cache/\"" >> $AGL_TOP/site.conf
ln -sf $AGL_TOP/site.conf conf/
```