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 buf-
       fers 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 per-
       formed) will be rejected and displayed on standard-error.

       If zero files are specified then there will be no error, it will just silently output nothing, this is for scripts which use the find  com-
       mand 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 stan-
       dard 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 number 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.company.com/ which allows programs like Webal-
	      izer 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@coker.com.au>.

SEE ALSO

       clfsplit(1),clfdomainsplit(1)

Russell Coker <;russell@coker.com.au>				       0.06							       clfmerge(1)