Re: Reading portions of large files

[Brendan Halpin <brendan.halpin@ul.ie>]

Gerald.Jean@spgdag.ca writes:

> I have very large files, sometimes over 1G, from which I would like to edit
> very small portions, the headers or trailers for example.  Emacs won't open
> those files, it complains about them being too big.  Is it possible to
> edit, and save back after editing, only small portions of such files.

Use head and tail to split the file into the header-to-be-edited
and the-rest. Edit the header-to-be-edited in emacs, save, then
concatenated the-rest onto it.

Assuming all editing is within the first 2000 bytes (not tested):

head -c2000 bigfile > header-to-be-edited
tail -c+2001 bigfile > the-rest
(edit header-to-be-edited, save)
cat header-to-be-edited the-rest > new-big-file

Even if the file is not too big to fit in Emacs, this should be
faster for very big files where the editing is all in a small
section. 

Brendan
-- 
Brendan Halpin,  Deptartment of Sociology,  University of Limerick,  Ireland
Tel: w +353-61-213147 f +353-61-202569 h +353-61-390476;  Room F2-025 x 3147
<mailto:brendan.halpin@ul.ie>        <http://wivenhoe.staff8.ul.ie/~brendan>