newbee

[Peter Otten]

Frank Scafidi wrote:

> I just acquired a Raspberry Pi and want to program in Python. I was a PL/1
> programmer back in the 60's & 70's and Python is similar. I am struggling
> with some very fundamental things that I am not finding in the
> documentation. Can someone help me with the basics like how do I save a
> program I've written, reload it in Python, list the program once it's
> loaded? How do I edit a program? Are these command line functions?

You can use any text editor to write a python script. A simple editor which 
might be present ont the Pi is called "nano". It shows the hotkeys to store 
the text and quit the editor, and thus should be self-explanatory:

$ nano helloworld.py

Once you have written your simple script you can look at it with the "cat" 
command:

$ cat helloworld.py 
#!/usr/bin/env python
print "Hello world"

Invoke it with:

$ python helloworld.py 
Hello world

You can also make your script "executable" which means that the first line 
controls which program is used to run it:

$ chmod +x helloworld.py 
$ ./helloworld.py 
Hello world
$

If the script is in a directory listed in the PATH environment variable you 
can omit the path (the "./" in the above example):

$ mv helloworld.py ~/bin
$ helloworld.py 
Hello world

PS: I ran the above demo on a Linux system, but not on the Raspberry Pi, so 
if something doesn't work as shown above it's probably due to the difference 
between the two systems.