[sf-lug] I need a quick piece of code..

jim jim at well.com
Thu Dec 31 10:08:03 PST 2009


   wrt problem definitions, maybe we can come up with 
several common parameters and general cases via email 
before the hoped-for python class that may or may not 
happen at noisebridge from 6:30 PM to 8 PM this coming 
monday (20100104)? (interested in a more-or-less 
intro to python and/or programming in general? this 
class has a flexible and accommodating format to let 
people just jump right in no matter their level.) 

   i like general parametric and problem definitions 
that can be used as specs for a variety of languages, 
(for my interests: shell scripts, c, and python) 

parametric specs: 
* all files are ASCII text files (note that numbers, 
therefore, are strings of text constrained to the 
ten numerals and perhaps the six alpha chars 
(a,b,c,d,e,f) for hex (and if so, uppercase and/or 
* types of numbers: phone numbers, dates, money, 
results of the four arithmetic operations, output 
of commonly used gnu toolkit commands (e.g. wc).... 
* common flatfile formats (e.g. /etc/passwd, which 
uses both the colon (:) and the comma (,) 
characters as field delimiters, the command line 
(and shell scripts) which typically (tho' not 
necessarily) use the space character as field 
(parameter) delimiters.... 
* a filter that can be used to parse the output 
of commands (which commands: who, ps, wc...?), 
probably should exercise the use of the cut 
command if implemented as a shell script: what's 
the python equivalent of the cut command? 
* anything involving the use of the find command 
(what's the python equivalent?). 

use case specs: 
* /etc/passwd and /etc/group (maybe the fifth 
field--the "comment" field--if it has 
comma-delimited contact info?). 
* shell scripts (parsing python or perl scripts 
seems a bit beyond). 
* various configuration files, the more regular 
the better (e.g. dns zone files)  
* simple flatfile use cases in which each "record" 
is on a line by itself and for which fields are 
delimited by some one character (and possibly 
allowing a sub-field delimiter, again e.g. the 
fifth field of the /etc/passwd file). this could 
include custom files such as a list of friends 
with contact info and birthdays, a ToDo list with 
dates and chores. again, the more regular the 
better. (i recall that larry wall developed perl 
from the c programs and shell scripts he'd 
created as his own toolkit to "parse" irregular 
text files. 

(stop me, i can't help myself...) 

On Thu, 2009-12-31 at 07:27 -0800, Alex Kleider wrote:
> It would be good to have the problem defined.
> So far the assumption has been that you want to return the last line of a file which you happen to know will be an integer- I'm doubting that that is the real problem.
> Could it be the more general problem of returning all integers? ..integers on single lines by them selves?  .. what are the other possibilities????
> This seems like the perfect little exercise for the python class held (over the holidays: somewhat irregularly) on Monday evenings.
> ak
> --- On Wed, 12/30/09, John F. Strazzarino <jstrazza at yahoo.com> wrote:
> > From: John F. Strazzarino <jstrazza at yahoo.com>
> > Subject: [sf-lug] I need a quick piece of code..
> > To: "SFLUG Mailing List" <sf-lug at linuxmafia.com>
> > Date: Wednesday, December 30, 2009, 10:25 PM
> > I
> > have a three line text file
> >  
> >  
> > This is a test
> > blank line
> > 123456
> >  
> >  
> > The last line of the file is a number and I need just
> > that number....
> >  
> > I know that this must be a combo of tail and grep
> > 
> >  
> > Can anyone help......nothing fancy is needed...
> > \\
> > Thanks
> >  
> > John
> >  
> > 
> > 
> >       
> > -----Inline Attachment Follows-----
> > 
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