Ubuntu Update file location

Ubuntu file location!

 
The software I installed with commands, such as sudo apt-Get install emerald !!! It all downloads first. I want to know where the download is. Can I copy it? You don't need to download it next time! There is also a system-system management-where is the video card downloaded by attaching hardware? Ask a senior!
 

 Backup and cleanup 
 Backup quick setup of some downloaded software packages, to re-use the system, no re-download time 
 tar cizvf backup.tar.gz/var/Cache/APT/archives -- exclude =/var/Cache/APT/archives/partial/* -- exclude = /var/Cache/APT/archives/lock 
 reinstall the system, after the source list is set, import the backed up software package. The procedure is as follows: sudo apt-Get Update & sudo tar xzvf backup.tar.gz-C/
 clear 
 sudo apt-Get clean 
 RM-RF ~ /. Thumbnails/fail/gnome-thumbnail-factory/* 
 the download directory is/var/Cache/APT/archives.