help need to "read from file until xxxx OR yyyy OR zzzz"
Frank D. Engel, Jr.
fde101 at fjrhome.net
Tue Dec 14 09:13:53 CST 2004
You should be able to read in an entire file of even several hundred
megabytes, assuming the rest of the data you have in memory is not too
excessively large. Most 32-bit operating systems leave a virtual
address space of just under 2GB for each program. In that 2GB you fit
your application program, some shared library code, the heap and stack
space, etc. -- but there should still be more than 1GB for your data.
Even if your computer only has 128MB of RAM, with modern hard drives
and virtual memory architecture... I'd figure on being able to handle
files of around 200MB on smaller semi-modern systems, maybe as big as
1GB or more on high-end systems, while loading the whole thing into
Note that this may vary somewhat depending on the operating system you
As far as using RegEx, you could only use it on the portion of the file
loaded into memory. You might consider doing that, and realize that if
there is no match, then you only have a part of the block in memory, so
read some more and try again...
On Dec 14, 2004, at 9:46 AM, Randy Padawer wrote:
> Thanks for the comments. Well, the problem with reading the whole file
> at once is that some of these files can indeed be huge -- several
> megabytes. Here's what I'm doing... The text file is made up of many
> individual emails concatenated end-to-end. Since the emails may have
> originated from different ISP accounts, they may use different
> delimeters, i.e., ">From " or "X-Message-Info: " or "Return-Path: <"
> or "From ???@???". I have written a simple program that will separate
> the huge file back into individual text files, one for each email. It
> works well if the email is from a single account (with its unique
> delimeter). However if, say, Apple's mail.app is pulling mail from
> multiple accounts, I can't "read from" any of those delimeters. Can I
> do the regex routine (something I don't quite yet understand... but
> will soon!) on a file I've not wholly read? Thanks again for your
> great help. -- Randy
> use-revolution mailing list
> use-revolution at lists.runrev.com
Frank D. Engel, Jr. <fde101 at fjrhome.net>
$ ln -s /usr/share/kjvbible /usr/manual
$ true | cat /usr/manual | grep "John 3:16"
John 3:16 For God so loved the world, that he gave his only begotten
Son, that whosoever believeth in him should not perish, but have
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