[Tutor] creating files and writing to them

[Michael P. Reilly]

> Hi Todd etc.--
> 
> Todd Martin wrote:
> > 
> > Ok so I can do these things in perl and shell but I'm just now learning
> > python and am a little confused.
> > 
> > What I want to do is pass a username to a script as an argument like so:
> > 
> > % script username
> > 
> > Then write a file named "username.startup".
> > 
> > This is where I'm at right now:
> > 
> > #! /usr/bin/python
> > 
> > file = open('/home/todd/docname', 'w')
> > file.write('The create script in its infancy\n')
> > file.close()
> > 
> > def docname ():
> >         username = "todd"
> >         startup = ".startup"
> >         doc = username + startup
> >         print "%s" % doc
> > 
> > docname()
> > 
> > I know its lame so far but I'm new :)
> > 
> > Ok so that last tidbit there is how I figured I could take the username and
> > append ".startup" to it. But now I need to create a file by that name, rather
> > than the way its being done now, where I have to declare the file name in
> > advance (does that make sense?).
> > 
> > Now I know I will need to pass the username argument to argv, but that can wait untill I find out how to pass file = open() a variable rather than a file name.
> > 
> > Is this clear? I'm not entirely sure I know how to word this right.
> > 
> > Any help would be very appreciated!
> > 
> 
> #!/usr/bin/python
> # I see that you're on RedHat Linux;-)
> if len ( sys.argv ) > 1 :
>   homedir = "/home/"
>   username = sys.argv[1]
>   startup = "/.startup"
> 
>   startupfile = open ( homedir + username + startup, 'w' )
>   file.write('The create script in its infancy\n')
>   file.close()
> else :
>   print "Usage:  %s username" % ( sys.argv[0] )

Just for a little, more portable, change (on UNIX): the expanduser()
function in the os.path module resolves "~username" from the
/etc/passwd file.

  if len(sys.argv) > 1:
    username = sys.argv[1]
    homedir = os.path.expanduser('~' + username)
    doc_filename = os.path.join(homedir, 'docname')
    doc_file = open(doc_filename, 'w')

    startupfile = open(username + '.startup', 'w')
    ...

Not all systems/users may have their home directories in "/home/".

  -Arcege