Clearly there are many more directories on the system—far too many to describe every one.
For changing things, you’ll usually want to confine yourself to your home directory and /etc. On a Debian system, there’s rarely an occasion to change anything else, because everything else is automatically installed for you.
/etc is used to configure the system as a whole. You’ll use your own home directory, a subdirectory of /home, for configuring your own preferences and storing your personal data. The idea is that on a day-to-day basis, you confine yourself to /home/yourname, so there’s no way you can break anything. Occasionally you log in as root to change something in a system-wide directory, but only when it’s absolutely necessary. Of course, if you’re using Debian at a school or business and someone else is the system administrator, you won’t have root access and will be able to change only your home directory and any other directory that you own. This limits what you can do with the system.
7.3 File Compression with gzip
Often it would be nice to make a file smaller—say, to download it faster, or so it takes up less space on your disk. The program to do this is called gzip (GNU zip). Here’s how it works:
$ cd; cp /etc/profile ./mysamplefile
This switches to your home directory and copies an arbitrarily chosen file (/etc/profile) to your current directory, in the process renaming it mysamplefile. This gives you a file to play with when using gzip.
$ ls -l
Lists the contents of the current directory. Note the size of mysamplefile.
$ gzip mysamplefile