outputting a command to the terminal?

[John Salerno]

Here's my new project: I want to write a little script that I can type 
at the terminal like this:

$ scriptname package1 [package2, ...]

where scriptname is my module name and any subsequent arguments are the 
names of Linux packages to install. Running the script as above will 
create this line:

sudo aptitude install package1 package2 ...

It will run that line at the terminal so the package(s) will be installed.

Now, the extra functionality I want to add (otherwise I would just 
install them normally!) is to save the package names to a text file so I 
can now the names of programs I've manually installed, if I ever want to 
check the list or remove packages.

So creating the proper bash command (sudo aptitude install ...) is easy, 
and writing the names to a file is easy. But I have two questions:

1. First of all, does Linux keep track of the packages you manually 
install? If so, then I won't have to do this at all.

2. Assuming I write this, how do output the bash command to the 
terminal? Is there a particular module that Python uses to interact with 
the terminal window that I can use to send the install command to the 
terminal?

Thanks.