use workdir properly hopefully

Dockerfile

@@ -1,5 +1,7 @@
 FROM debian:buster-slim
 
+WORKDIR /home/pi/pialert/
+
 #Update and reduce image size
 RUN apt-get update \
     && apt-get install --no-install-recommends apt-utils cron sudo lighttpd php php-cgi php-fpm php-sqlite3 sqlite3 dnsutils net-tools python iproute2 -y \
@@ -13,21 +15,21 @@ RUN apt-get update \
 
 # Lighttpd & PHP
 RUN mv /var/www/html/index.lighttpd.html /var/www/html/index.lighttpd.html.old \
-    && ln -s /home/pi/pialert/install/index.html /var/www/html/index.html \
+    && ln -s install/index.html /var/www/html/index.html \
     && lighttpd-enable-mod fastcgi-php 
 
 COPY . /home/pi/pialert
 
 # delete .git/ files and the tar/ realese directory to make the image smaller
-#RUN rm -r /home/pi/pialert/.git \
-RUN rm -r /home/pi/pialert/tar 
+#RUN rm -r .git \
+RUN rm -r tar 
 
 # Pi.Alert   
-RUN ln -s /home/pi/pialert/front /var/www/html/pialert  \
-    && python /home/pi/pialert/back/pialert.py update_vendors \    
-    && (crontab -l 2>/dev/null; cat /home/pi/pialert/install/pialert.cron) | crontab - \
-    && chgrp -R www-data /home/pi/pialert/db \
-    && chmod -R 770 /home/pi/pialert/db \
+RUN ln -s front /var/www/html/pialert  \
+    && python back/pialert.py update_vendors \    
+    && (crontab -l 2>/dev/null; cat install/pialert.cron) | crontab - \
+    && chgrp -R www-data db \
+    && chmod -R 770 db \
     # changing the default port number 80 to something random, here 20211
     && sed -ie 's/= 80/= 20211/g' /etc/lighttpd/lighttpd.conf \
     && service lighttpd restart 
@@ -36,6 +38,6 @@ RUN ln -s /home/pi/pialert/front /var/www/html/pialert  \
 EXPOSE 20211
 
 # Set up startup script to run two commands, cron and the lighttpd server
-RUN chmod +x /home/pi/pialert/dockerfiles/start.sh
+RUN chmod +x dockerfiles/start.sh
 
-CMD ["/home/pi/pialert/dockerfiles/start.sh"]
+CMD ["dockerfiles/start.sh"]