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Under GNU General Public License
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clfmerge(1) logtools clfmerge(1)
NAME
clfmerge - merge Common-Log Format web logs based on time-stamps
SYNOPSIS
clfmerge [--help | -h] [-b size] [-d] [file names]
DESCRIPTION
The clfmerge program is designed to avoid using sort to merge multiple web log
files. Web logs for big sites consist of multiple files in the >100M size range
from a number of machines. For such files it is not practical to use a program
such as gnusort to merge the files because the data is not always entirely in order
(so the merge option of gnusort doesn’t work so well), but it is not in random
order (so doing a complete sort would be a waste). Also the date field that is
being sorted on is not particularly easy to specify for gnusort (I have seen it
done but it was messy).
This program is designed to simply and quickly sort multiple large log files with
no need for temporary storage space or overly large buffers in memory (the memory
footprint is generally only a few megs).
OVERVIEW
It will take a number (from 0 to n) of file-names on the command line, it will open
them for reading and read CLF format web log data from them all. Lines which don’t
appear to be in CLF format (NB they aren’t parsed fully, only minimal parsing to
determine the date is performed) will be rejected and displayed on standard-error.
If zero files are specified then there will be no error, it will just silently out-
put nothing, this is for scripts which use the find command to find log files and
which can’t be counted on to find any log files, it saves doing an extra check in
your shell scripts.
If one file is specified then the data will be read into a 1000 line buffer and it
will be removed from the buffer (and displayed on standard output) in date order.
This is to handle the case of web servers which date entries on the connection time
but write them to the log at completion time and thus generate log files that
aren’t in order (Netscape web server does this - I haven’t checked what other web
servers do).
If more than one file is specified then a line will be read from each file, the
file that had the earliest time stamp will be read from until it returns a time
stamp later than one of the other files. Then the file with the earlier time stamp
will be read. With multiple files the buffer size is 1000 lines or 100 * the num-
ber of files (whichever is larger). When the buffer becomes full the first line
will be removed and displayed on standard output.
OPTIONS
-b buffer-size
Specify the buffer-size to use, if 0 is specified then it means to disable
the sliding-window sorting of the data which improves the speed.
-d Set domain-name mangling to on. This means that if a line starts with as
the name of the site that was requested then that would be removed from the
start of the line and the GET / would be changed to GET http://www.com-
pany.com/ which allows programs like Webalizer to produce good graphs for
large hosting sites. Also it will make the domain name in lower case.
EXIT STATUS
0 No errors
1 Bad parameters
2 Can’t open one of the specified files
3 Can’t write to output
AUTHOR
This program, its manual page, and the Debian package were written by Russell Coker
<russell AT coker.au>.
SEE ALSO
clfsplit(1),clfdomainsplit(1)
Russell Coker <russell AT coker.au> 0.06 clfmerge(1)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache/1.3.41 (Unix) PHP/5.2.5 mod_perl/1.30 mod_gzip/1.3.26.1a
Under GNU General Public License
2008-08-30 04:54 @38.103.63.61 CrawledBy CCBot/1.0 (+http://www.commoncrawl.org/bot.html)